Storage Unit Size Calculator

Tell us what you are storing, either by home size or item by item, and you get one specific unit size rather than a range. The field that changes the answer most is the one no size chart asks about: whether you need to walk in and reach things, which costs about a third of the space and usually one whole size.

By home size (quick) By items (accurate)

What are you putting in storage? (this is the whole contents. If you are storing part of a house, use the item list instead)

Will you need to get to things while it is in storage?

No, pack it tight Yes, I need a walkway

Ceiling height in feet (optional) (blank uses 8, which is standard. Try 6.5 to see what a sprinklered building costs you)

Show a rough monthly cost range?

No Yes

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Data reviewed: August 2026. Figures here come from published sources and change over time. How we verify

How storage unit sizing actually works

Every size guide you have read describes storage units in square feet, and then answers a question that has nothing to do with square feet. You are not laying your sofa out on a floor plan. You are stacking it, and the thing that decides whether your belongings fit is volume: the width times the depth times how high you can pile it.

That distinction is not academic. A 10 by 10 unit and a 5 by 20 unit both have 100 square feet of floor, and at a standard 8 foot ceiling both hold 800 cubic feet of raw space. They are the same size on paper and nothing alike to live with, because one of them is five feet wide and you cannot stand in it while it has anything in it. That is the part this page is built around.

So the arithmetic here runs in three moves. Work out how much stuff you have, in cubic feet. Work out how much of a unit's cube you can genuinely fill. Round up to the next real size, because you cannot rent 1.4 storage units and because running out of room is the failure people remember.

If you are in the middle of a move, this page and the moving cost estimator answer the two halves of the same afternoon: that one prices the truck and the crew, this one sizes the room your things sit in when the truck leaves. The volume figures underneath both come from the same place, which is the cubic feet a mover would write on your inventory.

The formula

raw volume = width × depth × ceiling height
usable volume = usable floor × ceiling height × 85% packing efficiency
usable floor, packed tight = width × depth
usable floor, with a walkway = (width less a 3 ft aisle) × depth
your load = every item × its cubic feet, added up
unit size = the first standard size whose usable volume covers your load, always rounded UP

The 85 percent is the air between a sofa arm and a mattress: real belongings do not tessellate, however carefully you load them. The 3 foot aisle is what operators' own packing guides recommend, and applying it as geometry rather than as a vague percentage produces the number this page exists to tell you. In a 10 foot wide unit an aisle costs exactly 30 percent of the floor. In a 5 foot wide unit it costs 60 percent, which is why a 5 wide unit is a load-it-and-shut-it unit rather than a room you visit.

Worked example

A two bedroom apartment, and you want to be able to get to things.

A two bedroom apartment works out to about 845 cubic feet of belongings: two mattress sets, a sofa and a loveseat, an armchair, four dressers and bookcases, a dining set, a desk, five small tables, two appliances, two TVs, two bikes, and 75 boxes.

Packed tight to the ceiling with no walkway, that fits a 10 by 15, which holds 1,020 cubic feet you can fill out of 1,200 raw. That is the answer nearly every operator's chart gives for a two bedroom, and it is correct for a unit you load once and open once.

Ask for a walkway and the arithmetic changes. A 3 foot aisle down a 10 by 15 takes 45 of its 150 square feet, leaving 714 cubic feet, and 845 does not fit in 714. You need a 10 by 20: 200 square feet, 1,600 cubic feet raw, 952 cubic feet you can actually fill, with 107 cubic feet of headroom. Nothing about your furniture changed. You just decided to be able to reach it.

That decision has a price, and it is smaller than people fear. At the national averages the largest operator publishes, a 10 by 15 runs $152 a month and a 10 by 20 runs $194. The walkway costs about $42 a month, or $504 a year. If you are going to open that door on a Saturday looking for one box, it is the best money in the rental. If everything goes in on one day and comes out on one day, save it.

One more figure worth knowing before you plan on filling the top foot. In a sprinklered building, fire code requires 18 inches of clear space below the sprinkler heads, so your real stack height is closer to 6.5 feet than 8. Run the same two bedroom at 6.5 feet with a walkway and the answer moves again, to a 10 by 25.

The stacking and access truth, which is the whole game

Here is the sentence that no operator's size chart contains, and it is the reason people rent units that turn out too small: every published capacity assumes you stack to the ceiling and never need to walk in.

Think about what "a 10 by 10 holds a two bedroom apartment" is actually claiming. It is claiming that 800 cubic feet of floor-to-ceiling solid loading, with your things pressed against the back wall and the door closing on the last box, will swallow two bedrooms. That is a real and achievable way to use a storage unit. It is just not the way most people use one. Most people open the door in March looking for the camping gear, and discover that reaching it means unloading the front half of the unit onto the corridor floor.

The moment you decide you need to reach things, you have to give up an aisle, and the aisle is not a rounding error. Operators' own packing guides recommend two to three feet of central walkway. A 3 foot aisle running the depth of a 10 foot wide unit takes 30 percent of the floor, and floor is what carries the stack, so it takes 30 percent of your capacity with it. That is very close to the "you lose about a third" figure people quote without ever showing the arithmetic.

Narrow units are worse, and the difference is not intuitive. That same 3 foot aisle in a 5 foot wide unit leaves a strip two feet wide. You cannot store a mattress set in a two foot strip. This is why the honest description of a 5 by 5, a 5 by 10, or a 5 by 15 is not "a small unit" but "a unit you load from the doorway", and why the jump from a 5 wide to a 10 wide is a much bigger jump in usefulness than it is in square feet.

So decide the access question before you decide the size, not after. If this is a move, a deployment, a renovation, or a house sale, you almost certainly want the small unit packed solid. If this is a business storing inventory, a family storing seasonal things, or anyone who will be back inside that unit more than twice, buy the aisle. It costs one size, which is usually $30 to $60 a month, and it is the difference between a storage unit and a very expensive box you are afraid of.

What actually fits in each size, in plain terms

These are the descriptions operators use, cross checked against four published size guides, with the cubic feet that sit underneath them at a standard 8 foot ceiling. The last column is the honest one: what you can fill if you want to be able to walk in.

Unit size	Floor	Raw cubic feet	Fill packed	Fill with a walkway	Usually described as
4 by 5 locker	20 sq ft	80	68	17	A closet shelf: boxes, decorations, a small wardrobe
5 by 5	25 sq ft	200	170	68	A large closet: a twin mattress, a small dresser, 5 to 8 boxes
5 by 10	50 sq ft	400	340	136	A studio apartment, or one fully furnished bedroom
5 by 15	75 sq ft	600	510	204	A one bedroom apartment, or a bedroom plus appliances
10 by 10	100 sq ft	800	680	476	Two bedrooms, or a whole living room and then some
10 by 15	150 sq ft	1,200	1,020	714	A two bedroom apartment
10 by 20	200 sq ft	1,600	1,360	952	A three bedroom home, or a car
10 by 25	250 sq ft	2,000	1,700	1,190	A three to four bedroom home
10 by 30	300 sq ft	2,400	2,040	1,428	A four bedroom home, or a household plus a vehicle

Two things to notice. The raw cubic feet column is just the square footage times 8, which is exactly how Extra Space Storage and Public Storage both publish it, so if you have seen those numbers before this is where they came from. And the gap between the two fill columns is the whole argument of this page: a 10 by 15 is either a two bedroom apartment or a one bedroom apartment, depending entirely on whether you want to be able to get inside it.

If you have found three different answers, the problem was never you

We read four published size guides carefully before building this, and they land in different places. That is not anybody behaving badly. Sizing storage is genuinely fuzzy, the charts are written to be quickly helpful rather than precise, and a furnished two bedroom and a spartan two bedroom are simply not the same job. Here is the real spread, so you can stop wondering which one to believe, including ours.

A one bedroom apartment is quoted anywhere from a 5 by 15 to a 10 by 10, which is 75 to 100 square feet for the same three words. Both are defensible, and the thing that decides it is whether the apartment came furnished.

A three bedroom house is quoted at a 10 by 20 in some places and a 10 by 25 in others, sometimes within the same guide. That is a 25 percent difference in floor area, and it comes down to how tightly you intend to pack and whether the garage is coming too.

A two bedroom answer quietly depends on a number no chart asks you for. One operator's guide says a 10 by 15; its own blog says a 10 by 10 up to about 800 square feet and a 10 by 15 above that. Both are true. The hidden variable is the size of the apartment, and once you know that is the variable, every chart you read makes more sense.

For what it is worth: our packed mode reproduces the consensus of those four guides for every home size from a studio to a four bedroom house, which is how we chose the 85 percent packing figure rather than picking a number we liked. Where we differ from all of them is the walkway, and we differ deliberately.

Things worth knowing before you sign

None of this changes the size. All of it changes whether you are happy in six months, and any decent facility manager will tell you the same things.

Climate control, and what genuinely needs it. The list is shorter than the upsell suggests: solid wood furniture, leather, musical instruments, electronics, photographs, artwork, documents, vinyl, and anything with adhesive in it. The mechanism worth understanding is not steady humidity, it is the daily cycle. A metal-roofed unit swings thirty degrees between afternoon and dawn, air hits its dew point, moisture beads on cold surfaces inside your things, and evaporates by lunchtime. That wet-dry cycle is what warps a table top and corrodes a circuit board. If it is a few months of patio furniture, plastic bins, and a lawn mower, skip it. If it is a piano, a sofa you like, or a hard drive, do not. Expect to pay roughly 15 to 30 percent more, and up to 50 percent in some markets.

Ground floor versus upper floor, and drive-up versus interior. A drive-up unit means you back a truck to the roll door and carry nothing. An interior unit on the ground floor means a cart and a corridor. An upper floor unit means an elevator, and an elevator means a queue on the first Saturday of the month when everybody else in the building is also moving. Upper floor units are cheaper for exactly this reason and they are a fine deal if you will visit twice a year. If you are moving a household in one day with rented help on the clock, pay for the drive-up.

Insurance is usually not optional. Every major operator requires coverage as a condition of the lease, and they will sell you a policy at the counter. Before you take it, check what you already have: renters and homeowners policies typically cover belongings away from home at around 10 percent of your personal property limit, which for many people is enough and is already paid for. Bring the declarations page. The facility will accept proof of your own coverage.

What you cannot store, and the ones that surprise people. No perishable food, no plants, no animals, ever. No flammables or combustibles, which means gasoline, propane, kerosene, paint, solvents, aerosols, fertilizer, and pool chemicals. Drain the mower and the trimmer before they go in. No lithium batteries in many leases now. Nothing living, nothing that was recently alive, and nobody sleeping there. Tires are frequently restricted because facilities cannot dispose of them. And the practical one nobody writes down: a single forgotten grocery bag will introduce mice to a hundred neighboring units, which is why the food rule is the one facilities enforce hardest.

Load it so future you can use it. Leave the aisle if you paid for it. Put anything you might need at the front and label the boxes on the side that faces the aisle rather than the top, because you will be reading them from the front of a stack. Heavy on the bottom, fragile on top, nothing directly on a concrete floor if you can help it (a pallet, a plank, or even flattened cardboard stops moisture wicking up). Stand mattresses and sofas on end to reclaim floor. Fill the inside of every drawer, every suitcase, and the washing machine drum. Take doors and legs off what you can and tape the hardware to the piece. Boxes of uniform size stack; boxes of random size do not, and that single choice moves your usable capacity more than any other packing tip.

And measure your own life, not a chart. Ours is a good starting number and a very good way to sanity check what a facility tells you. It is not a substitute for standing in an empty unit with a tape measure, which takes ten minutes and which any facility will happily let you do. If you are between the sizes, take the bigger one. Nobody in the history of self storage has stood in a half empty unit and wished it were smaller.

Sources

Where the numbers on this page come from. We go to the body that publishes the figure, not to another calculator. Figures on this page were checked against these sources in August 2026. See how we verify.

Storage Unit Size Guide, Extra Space Storage. MEASURED as published, and the single most useful source on this page for two opposite reasons. First, it prints the full size ladder with square feet and cubic feet: 5x5 25/200, 5x10 50/400, 5x15 75/600, 10x10 100/800, 10x15 150/1200, 10x20 200/1600, 10x25 250/2000, 10x30 300/2400, with the footnote that cubic feet is calculated at a typical 8 foot unit height. It also states plainly that storage units are typically 8 feet tall, that select units run 10 feet or taller, and that reduced height units are sold in expensive metros at the same square footage for a lower price. Lockers are listed at 2x2 through 5x5 with heights between 3 and 5 feet, which is where our locker row comes from. Second, and this is the finding the page reports, it answers the same question three different ways on one page. Its size chart lists 10x20 as 3 Bedrooms. Its bullet list reads 3-4 bedroom: 10x20 storage unit and then on the very next line 3-4 bedrooms: 10x25 storage unit. Its FAQ at the bottom of the same page says a 10x25 typically fits the contents of a 3-bedroom home. That is a 25 percent spread in floor area from one publisher without leaving the URL. The same page also supplies the operator average prices we quote (5x5 $36, 5x10 $61, 5x15 $85, 10x10 $109, 10x15 $152, 10x20 $194, 10x30 $269) and the statement that insurance is required when storing your items in a storage unit. This site returns 403 to automated fetches, so it was read in a real browser.
Self-Storage Unit Size Guide, Public Storage. MEASURED as published, and the second full mapping. 5x5 25 sq ft / 200 cu ft, fits the contents of one storage closet; 5x10 50/400, a studio apartment; 5x15 75/600, a large bedroom; 10x10 100/800, two small bedrooms; 10x15 150/1200, a two-bedroom home; 10x20 200/1600, a three-bedroom home; 10x25 250/2000, a four-bedroom home. Note that every cubic feet figure here is exactly the square footage times 8, which is the second independent confirmation of the standard ceiling height. This operator also disagrees with itself across pages rather than within one: its own blog says that for most two-bedroom apartments up to 800 square feet a 10x10 does the job, and a 10x15 if the apartment is bigger, while the size guide above assigns the two-bedroom home to the 10x15 outright. Both are defensible. The point is that the answer depends on the apartment's square footage, which no size chart asks you for.
Self Storage Unit Sizes and Storage Unit Size Guide, SelfStorage.com and Modern Storage. REPORTED, the third and fourth mappings, used to establish where the industry consensus actually sits. SelfStorage.com: 5x5 a compact hallway closet, 5x10 a queen bed set and TV and boxes, 5x15 a large walk-in closet, 10x10 a small to average bedroom or living room contents, 10x15 two-bedroom apartment contents, 10x20 full home contents, 10x25 3-4 bedroom home contents, 10x30 a fully furnished 4-bedroom home, all at an 8 ft ceiling with lockers listed under 8 ft. Modern Storage: 5x5 walk-in closet, 5x10 studio apartment or single room, 10x10 one-bedroom apartment, 10x15 two-bedroom apartment or small home, 10x20 three-bedroom home, 10x30 four to five bedroom home or two-car garage. The one bedroom row is where the four guides spread widest: Extra Space says 5x15, Modern Storage says 10x10, and Public Storage puts a large bedroom in the 5x15 without answering the apartment question. Our packed mode reproduces the modal answer of these four guides for every home size from a studio through a four bedroom house, which is how the 85 percent packing figure was chosen rather than invented.
Move volume estimator and cubic feet by home type, MoveRight. REPORTED, one of the two independent cube tables behind every item figure on this page. Per item: king bed and frame 55, queen bed and frame 45, full/double bed 35, 3-drawer dresser 20, 6-drawer dresser 30, sofa 3-seat 50, loveseat 35, armchair 25, dining table 6-person 40, dining chair 8, 50 inch TV and stand 20, refrigerator 40, washer 30, dryer 25, desk 25, bookcase 5-shelf 30, medium box 3, wardrobe box 12. Per home, low / typical / high: studio 200/350/500, 1-bedroom 400/550/750, 2-bedroom 700/900/1,200, 3-bedroom 1,000/1,500/2,000, 4-bedroom 1,500/2,200/3,000, 5+ 2,500/3,500/5,000+.
How many cubic feet do I need, and Estimating Cubic Feet, MovingTruckSize.com and Guy With a Truck. REPORTED, the second and third cube tables, used to bracket the first. MovingTruckSize per home: studio 200 to 400, 1-bedroom 400 to 600, 2-bedroom 800 to 1,200, 3-bedroom 1,200 to 1,600, 4-bedroom 1,800 and up. Per item: sofa 3-seat 45 to 60, recliner 25 to 30, coffee table 10 to 15, large TV 10 to 15, queen bed with mattress 55 to 65, dresser 6-drawer 30 to 45, dining table 4-person 20 to 30 with four chairs 10 to 12 total, refrigerator 45 to 60, washer and dryer together 40 to 60, bicycles 10 to 15 each, mower 15 to 25, boxes 1.5 to 5. A mover's cube sheet adds twin mattress 25, queen 60, king 70, bed frame 10, large dresser 35, 3-seat couch 60, loveseat 35, tall bookshelf 20, large desk 25, refrigerator 60, washer 25 to 30, stove 30, small box 1.5, medium box 3, large box 4.5 to 6. Our per item figures are the middle of where these lists overlap. The honest sore spot is the dining row: one source implies about 72 cubic feet for a table with four chairs and another implies 30 to 42, because chairs stack in real life and do not on a cube sheet. We use 40 and say so. Our per home figures are NOT taken from these tables. They are computed by summing a representative inventory through our own item list, and a test asserts every one of those sums lands inside the overlap of the two published bands above.
Standard moving box dimensions, U-Haul. MEASURED, and the only figure on this page that needs no estimating at all. Small box 16-3/8 by 12-5/8 by 12-5/8 inches, which is 1.51 cubic feet. Medium 18-1/8 by 18 by 16, which is 3.02. Large 18 by 18 by 24, which is exactly 4.5. Extra large 24 by 18 by 24, which is exactly 6.0. Our boxes row uses the medium box at 3 cubic feet because it is the one people own the most of, and the test suite derives 4.5 and 6.0 from the inch dimensions and 1,728 cubic inches per cubic foot rather than trusting the printed label.
NFPA 13, clearance to storage below sprinkler deflectors, National Fire Protection Association, via UpCodes. MEASURED, and the reason the ceiling field on this page is not decoration. A minimum of 18 inches must be maintained between the sprinkler deflector and the top of storage, and that 18 inch clearance is treated as a horizontal plane across the whole storage area, with a narrow exception for wall shelving not directly below a sprinkler. In a sprinklered building with a nominal 8 foot ceiling that leaves about 6.5 feet of legal stack height, which is 19 percent of the cube you thought you were renting. We deliberately do NOT apply this silently, because not every unit sits under a head and partition walls in many facilities stop below the building deck. It is taught in the steps and the ceiling field is where a user acts on it.
2026 storage unit pricing guides, StorageStar and Parachute Storage. REPORTED, the two guides behind the optional cost band, which defaults to OFF so that a facility can embed this page without a price band appearing on its own site unless it asks for one. StorageStar monthly: 5x5 $50 to $70, 5x10 $80 to $110, 10x10 $120 to $160, 10x15 $160 to $210, 10x20 $200 to $270, 10x30 $300 to $400, with climate control about 17 percent more. Parachute monthly: 5x5 $40 to $80, 5x10 $60 to $120, 10x10 $100 to $160, 10x15 $130 to $200, 10x20 $150 to $300, 10x30 $200 to $350, with climate control adding 20 to 50 percent, and coastal metros charging 50 to 100 percent more than inland markets for the same unit. Our band per size runs from the lower low to the higher high of the two, and the locker, 5x15 and 10x25 rows are interpolated between neighbours and labeled as interpolated on the page. The climate premium is quoted as 15 to 30 percent, which is where the published figures cluster (10 to 20, up to 19, 15 to 25, 17, and 20 to 50 across five sources). Worth noticing on its own: the largest operator's own published national average lands in the bottom half of the combined band at every single size, and below the low end of the dearer of the two guides at every size where that guide publishes one (36 against 50, 61 against 80, 109 against 120, 152 against 160, 194 against 200, 269 against 300).
Storage insurance, and what cannot be stored, Extra Space Storage, Public Storage, and Move.org. REPORTED. Insurance: every major operator, including CubeSmart, Extra Space, Public Storage, U-Haul and Simply Self Storage, requires coverage as a condition of the lease and sells a policy at the counter. Renters and homeowners policies typically cover personal property away from the residence at around 10 percent of the personal property limit, subject to exclusions, and facilities accept proof of your own coverage. Prohibited items, consistent across operator lease terms: perishable food, live plants, animals, people, flammables and combustibles (gasoline, propane, kerosene, paint, solvents, aerosols, fertilizer, pool chemicals), explosives, drugs, and increasingly lithium batteries. Tires are frequently restricted because facilities cannot dispose of them. The food rule is the one facilities enforce hardest, because one forgotten grocery bag is a pest problem for every unit on the corridor.

Frequently asked questions

What size storage unit do I need for a 2 bedroom apartment?

A 10x15 if you are packing it tight to the ceiling, and a 10x20 if you want to be able to walk in and reach things. A two bedroom apartment runs about 845 cubic feet of belongings. A 10x15 gives you 1,020 cubic feet of fillable space packed solid, but only 714 once a three foot walkway takes 30 percent of the floor. Operators generally quote 10x10 or 10x15 for a two bedroom, and the smaller answer assumes an apartment under about 800 square feet and no aisle.

How much fits in a 10x10 storage unit?

100 square feet of floor and 800 cubic feet of raw space at a standard 8 foot ceiling, of which you can realistically fill about 680 packed solid or 476 with a walkway down the middle. Here is exactly 680: two mattress sets, a sofa and a loveseat, four dressers or bookcases, a dining set, a desk, five side tables, two large appliances, two TVs, and 45 boxes. That is most of a two bedroom apartment but not all of it. With an aisle down the middle a 10x10 is closer to a one bedroom.

What size storage unit do I need for a 3 bedroom house?

A 10x20 packed tight, or a 10x30 if you need to walk in. A three bedroom house comes to roughly 1,235 cubic feet, and a 10x20 holds about 1,360 fillable packed but only 952 with an aisle. This is the size question where published guidance spreads widest: the largest operator in the country answers it as a 10x20 in its chart, a 10x20 or 10x25 in its bullet list, and a 10x25 in its FAQ, all on the same page.

Do I need climate controlled storage?

Only for things that care about the daily temperature swing: solid wood furniture, leather, instruments, electronics, photographs, artwork, documents, and vinyl. The damage mechanism is the cycle rather than steady humidity. A metal roofed unit swings thirty degrees between afternoon and dawn, moisture condenses on cold surfaces inside your things, and the wet-dry cycle warps a table top and corrodes a circuit board. Patio furniture, plastic bins, and a lawn mower for one summer do not need it. Expect roughly 15 to 30 percent more, and up to 50 percent in some markets.

How tall is a storage unit?

About 8 feet almost everywhere, and it is a property of the building rather than of the unit, so a 5x5 and a 10x20 in the same facility have the same ceiling. Drive-up and vehicle units run 10 to 12 feet, lockers are 3 to 5, and facilities in expensive cities sell reduced height units at the same square footage for a lower price. One thing that quietly shortens all of it: in a sprinklered building, fire code requires 18 inches of clear space below the sprinkler heads, so your legal stack height is closer to 6.5 feet than 8.

What size storage unit do I need for a 1 bedroom apartment?

A 5x15 packed tight, or a 10x10 if you want access. This is the row where published guides land furthest apart, quoting anywhere from a 5x15 to a 10x10 for the same three words, and both answers are defensible depending on whether the apartment came furnished. The honest tiebreaker is width rather than area. A 5 foot wide unit cannot take a walkway, so it is a load-it-and-shut-it unit no matter what fits in it.

How much does a storage unit cost per month?

Published 2026 guidance runs roughly $40 to $80 for a 5x5, $60 to $120 for a 5x10, $100 to $160 for a 10x10, $130 to $210 for a 10x15, $150 to $300 for a 10x20, and $200 to $400 for a 10x30. Worth knowing: the largest operator in the country publishes its own national averages at $36, $61, $109, $152, $194 and $269 for those same sizes, which lands in the bottom half of every published band and below the low end of the dearer guide at every size. Climate control adds 15 to 30 percent, and coastal metros run 50 to 100 percent above inland markets.

What can you not store in a storage unit?

Nothing perishable, nothing living, and nothing that burns. That means no food, no plants, no animals, and no gasoline, propane, kerosene, paint, solvents, aerosols, fertilizer, or pool chemicals, so drain the mower and the trimmer before they go in. Many leases now also exclude lithium batteries, and tires are frequently restricted because facilities cannot dispose of them. The food rule is the one enforced hardest, because one forgotten grocery bag becomes a pest problem for every unit on the corridor. Nobody may live or sleep in a unit.