Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Annual idle fuel cost
$9,804
Annual savings with APU/heater
$7,843
APU payback period
1.08
Annual idle gallons burned
2,482
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How to use this
- 1Enter average idle hours per day (hr/day).
- 2Enter idle fuel burn rate (gal/hr).
- 3Enter diesel price ($/gal).
- 4Enter apu/bunk heater investment ($).
- 5Enter idle fuel reduction with apu (%).
- 6Read your annual idle fuel cost on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
A long-haul truck idling overnight for climate control and hotel load burns roughly 0.8-1.0 gallons per hour depending on engine size and ambient temperature, and drivers who idle 8-10 hours a night can burn through 1,500+ gallons a year just sitting still. This calculator multiplies your average idle hours per day by idle fuel burn rate and diesel price to show annual idle fuel cost, and compares it against the cost of an APU (auxiliary power unit) or bunk heater investment to show the payback period — often under two years for drivers who idle heavily.
Worked example
Using the values the calculator loads with:
Inputs
- Average idle hours per day: 8 hr/day
- Idle fuel burn rate: 0.85 gal/hr
- Diesel price: 3.95 $/gal
- APU/bunk heater investment: 8500 $
- Idle fuel reduction with APU: 80 %
Results
- Annual idle fuel cost: $9,804
- Annual savings with APU/heater: $7,843
- APU payback period: 1.08
- Annual idle gallons burned: 2,482
What each field means
Inputs
- Average idle hours per day (hr/day)
- The average idle hours per day used in the calculation, measured in hr/day. Starts at 8 hr/day so you have a working example on load.
- Idle fuel burn rate (gal/hr)
- The idle fuel burn rate used in the calculation, measured in gal/hr. Starts at 0.85 gal/hr so you have a working example on load.
- Diesel price ($/gal)
- The diesel price used in the calculation, measured in $/gal. Starts at 3.95 $/gal so you have a working example on load.
- APU/bunk heater investment ($)
- The apu/bunk heater investment used in the calculation, measured in $. Starts at 8500 $ so you have a working example on load.
- Idle fuel reduction with APU (%)
- The idle fuel reduction with apu used in the calculation, measured in %. Starts at 80 % so you have a working example on load. Accepted range: 0–100 %.
Results
- Annual idle fuel cost
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual savings with APU/heater
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- APU payback period
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual idle gallons burned
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How much fuel does idling really burn?
A typical Class 8 sleeper idles at 0.6-1.0 gallons per hour depending on engine size, block heater use, and accessory load. Over a year of nightly idling that adds up to 1,000-1,800+ gallons — often 5-8% of a long-haul truck's total annual fuel spend.
Are there rules against idling?
Many states and some municipalities have idle-limit laws (commonly 5 minutes) with exceptions for extreme temperatures or mandatory rest periods, and truck stops increasingly meter idle time or offer paid shore-power/HVAC hookups as an alternative.
Is an APU worth it for every driver?
It pencils out fastest for drivers who idle 6+ hours nightly in variable climates. Drivers who mostly run in mild climates or use truck stop electrification services may find the payback period too long to justify the upfront cost and added maintenance.
What other options reduce idle cost besides an APU?
Bunk heaters (diesel-fired, cheaper than a full APU) handle heat but not AC; battery-electric APUs handle both but cost more upfront; truck stop shore power costs a nightly fee but requires no capital investment and no added maintenance.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Truck Idle Time Fuel Cost Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/truck-idle-time-cost
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/truck-idle-time-cost" target="_blank" rel="noopener">Truck Idle Time Fuel Cost Calculator — RevenueLab</a> (2026).</p>
Source: [Truck Idle Time Fuel Cost Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/truck-idle-time-cost) (2026).