How the soil math works
Soil is sold by volume — cubic yards in bulk, cubic feet in bags — but you measure your project as an area plus a depth. The conversion is one multiplication: area in square feet times depth in feet (inches ÷ 12) gives cubic feet, and dividing by 27 gives cubic yards. The number that surprises people is how big a cubic yard actually is: 27 cubic feet is a 3 × 3 × 3 ft cube — picture a washing machine and a half. It looks enormous in a driveway and then somehow disappears into the garden.
The formula
Area is length × width in feet (or enter the square footage directly for odd shapes). Bag count is cubic feet divided by the bag size, rounded up. Weight assumes topsoil at roughly 2,000–2,200 lbs per cubic yard — this calculator uses 2,100 as the midpoint; wet soil weighs noticeably more.
Worked example
Topping up a 10 × 20 ft vegetable garden with 4 inches of soil: 200 sq ft × (4 ÷ 12) = 66.67 cu ft, which is 66.67 ÷ 27 = 2.469 → 2.47 cu yd rounded up.
In 1.5 cu ft bags that's 66.67 ÷ 1.5 = 45 bags, and the load weighs about 2.47 × 2,100 ≈ 5,200 lbs (2.6 tons). Forty-five bags at two and a half tons is a bulk-delivery order, not a car-trunk errand.
Bags or bulk — and why to order extra
The break-even sits right around one cubic yard. Below it, bags win: no delivery fee, no dirt pile on the driveway, and you can stash spares. Above it, bulk soil usually costs a third to half of what the same volume costs in bags — the markup on bagged soil is mostly plastic and handling. One more thing the math won't tell you: fresh loose soil settles 10-15% once it's watered in and the air pockets collapse. A raised bed filled flush to the top in April sits two inches low by June. For beds you want genuinely full, order 10-15% over the calculated volume — it's the difference between topping off once and buying a second delivery.