Idle Cost Calculator
An idling engine is a machine for turning fuel into nothing, and the only question is how fast. Pick a vehicle, tell this how many hours it idles, and it prices the year in gallons, dollars and CO2, for one vehicle or a fleet. The rates come from Argonne National Laboratory's idling research, and the page checks the famous claims honestly, including the contractor who says his electric truck's savings cover the payment.
The formula
Nothing subtle in the arithmetic; the subtlety is that nobody counts the hours. Lunch in the cab with the AC running, the warm-up nobody timed, the twenty minutes of paperwork with the radio on, the queue at the scale: a work vehicle collects idle hours the way a couch collects coins, and at half a gallon an hour they price out to real money by December. The burn rates here come from Argonne National Laboratory's idling research: 0.16 gallons an hour for a compact car, 0.39 for a large sedan with accessories running, around 0.8 for a heavy diesel, more with load and air conditioning. Our work-pickup figure of 0.5 is a stated midpoint between the large-car measurement and the heavy-truck one, and the override box exists because your telematics knows your trucks better than any table.
Worked example: the job-site truck
A work pickup idling 3 hours a day across 250 working days at $4.15 gas:
0.5 × 3 × 250 = 375 gallons burned going nowhere, which is $1,556.25 a year and about 3.3 tons of CO2. Ten trucks doing the same is $15,562 a year, which is the moment a fleet manager stops calling it a rounding error.
The viral claim, checked: does an electric truck's idle savings cover the payment?
The post everyone has seen: a contractor switches his diesel work truck for an electric one and says the daily savings nearly cover the monthly payment. Here is the honest arithmetic. An EV holding cabin climate on a site draws roughly 1.5 kWh an hour, about 27 cents at home electricity rates, against roughly $2.08 an hour for the gas pickup above. The same 750-hour site year costs about $202 instead of $1,556: a saving of about $113 a month. That alone does not cover a truck payment. But idling is only half of a work truck's day: add the driving savings (our EV savings calculator prices those honestly, winter losses included) and a heavy-use site truck can genuinely push the combined figure toward a meaningful share of a payment. The claim rounds up, as viral claims do; the arithmetic under it is real, and now you can run it with your own hours.
Patrol cars: the fleet where idle is the whole story
A patrol vehicle's shift largely happens while parked: radios, cameras, computers and climate control run for hours with the odometer still. That is why police fleets sit at the extreme of this arithmetic, and why electric patrol pilots lead with idle economics rather than driving range. Set the vehicle to the large SUV, give it a shift's worth of idle hours and your department's fleet count, and the annual figure explains those pilot programs faster than any brochure.
Long-haul: a billion gallons parked at rest stops
Argonne counts more than a million long-haul trucks idling through federally required rest periods, burning over a billion gallons a year between them. One truck idling the commonly cited 1,830 hours a year at 0.8 gallons an hour burns about 1,464 gallons, roughly $8,600 at current diesel prices, which is the budget line that pays for auxiliary power units, battery HVAC systems and electrified parking spaces. Nationally, across every vehicle type, idling consumes more than 6 billion gallons a year: fuel purchased, refined, delivered and burned to travel zero miles.
Two rules worth keeping
First, the ten-second rule: for a modern engine, idling longer than about ten seconds uses more fuel than switching off and restarting, and modern starters shrug off the cycles; the let-it-run advice is a carburetor-era survivor. Second, the wear convention: fleet maintenance commonly counts an hour of idle as 25 to 30 miles of engine wear, which is why high-idle vehicles are serviced on engine hours. The fuel cost calculator prices the miles you actually drive, the MPG calculator measures what your engine really returns, and the trucking cost per mile calculator puts idle in its place among everything else a truck costs.
Data reviewed: September 2026. Figures here come from published sources and change over time. How we verify
Copy one snippet and give your visitors a working Idle Cost Calculator.
Frequently asked questions
How much fuel does idling use per hour?
From Argonne National Laboratory's measurements: a compact car idles at about 0.16 gallons per hour, a large sedan or SUV with accessories running around 0.39, and a heavy-duty diesel truck around 0.8, rising with load and air conditioning. A work pickup sits near half a gallon an hour. Small numbers per hour; the year is where they get expensive.
How much does idling cost a work truck per year?
A pickup idling three hours a day on job sites, 250 working days a year, burns about 375 gallons going nowhere: roughly $1,556 at current gas prices, plus about 3.3 tons of CO2. Three hours sounds high until you count lunch, paperwork, warm-up, and running the cab's heat or air conditioning all day, which is exactly how site trucks actually get used.
Does switching to an electric truck really cover the payment, like the viral posts say?
Partly, and the direction is right. An EV holding its cabin climate uses roughly 1.5 kWh an hour, about 27 cents at home rates, against roughly $2 an hour for a gas truck at idle: the same three-hour-a-day site year costs about $200 instead of $1,556, saving about $113 a month. That alone does not cover a typical truck payment, but idle is only half the story; add the driving savings our EV savings calculator prices and a heavy-use work truck can genuinely get close. The claim rounds up; the arithmetic underneath it is real.
Why do police vehicles idle so much?
Because the shift happens in the car: radios, cameras, computers and climate control run whether it is moving or parked, so patrol vehicles commonly idle for a large share of their engine hours. It is why fleet electrification pitches lead with patrol duty, where an engine that idles nearly free changes the arithmetic more than the driving does, and why this page lets you price a whole fleet at once.
How much do long-haul trucks lose to overnight idling?
Argonne reports more than a million long-haul trucks idling through required rest stops, over a billion gallons of fuel a year between them. One truck idling the commonly cited 1,830 hours a year at 0.8 gallons an hour burns about 1,464 gallons, roughly $8,600 at current diesel prices, which is why auxiliary power units and truck-stop electrification pay for themselves.
Is it better to idle or restart the engine?
Restart. For a modern engine, idling more than about ten seconds uses more fuel than switching off and starting again, and restarting causes negligible wear on modern starters. The old advice to let the engine run came from carburetor-era cars and it has outlived them by decades.
Does idling hurt the engine?
It is not free. Fleet maintenance conventions commonly count an hour of idling as equivalent to 25 to 30 miles of engine wear, since the engine turns thousands of revolutions while the odometer records nothing. That is an industry convention rather than a law of physics, but it is why high-idle fleet vehicles are serviced by engine hours, not miles.
How big is idling nationally?
Argonne estimates more than 6 billion gallons of gasoline and diesel are lost to idling every year in the US across all vehicle types. At today's prices that is on the order of $25 billion of fuel purchased to go exactly nowhere, which is the sort of number that makes a three-hour job-site idle feel less innocent.