Idle cost per hour is the fuel an idling engine burns multiplied by the price of diesel, plus wear that most fleets never price. At about 0.8 gallons an hour and $3.75 a gallon, one idle hour costs about $3.00 in fuel, which adds up to roughly $5,400 a year for a truck that idles 1,800 hours. This page gives the formula, rate tables you can read your fleet off, the idle-reduction options with their paybacks and a checklist to cut idle hours. Schedule a call to measure idle hours and cost across your fleet.
IDLE COST · RATE TABLES, PAYBACKS AND FORMULA
A Truck That Sits Running 1,800 Hours Burns About $5,400 of Diesel Going Nowhere
Read your idle cost off the tables, see what each reduction option pays back and put idle hours on a schedule you can track.
ONE IDLE HOUR, ILLUSTRATIVE
Fuel burned0.8 gal
Fuel cost at $3.75$3.00
Wear and maintenanceNot priced
Burn rate from Argonne. Price is an assumption.
The Idle Cost per Hour Formula
Fuel burn times fuel price gives the hourly cost, and idle hours turn it into a yearly figure
PER HOUR
Gallons per idle hour x price per gallon
Argonne uses 0.8 gallons an hour, with a range of 0.6 to 1.5.
PER YEAR
Cost per hour x idle hours a year
Long-haul trucks idle about 1,800 hours a year, per Argonne.
SAVINGS
Annual idle cost x percent reduction
A 20 percent cut is described as achievable with the right mix.
The U.S. Department of Energy's Argonne National Laboratory says a heavy-duty truck burns about 0.8 gallons of diesel an hour idling, and a long-haul truck idles about 1,800 hours a year, using about 1,500 gallons. Its cost table gives a wider range of 0.6 to 1.5 gallons an hour, and the burn rate varies with engine, load and weather. These are 2015 and 2017 figures, so check your own fuel logs.
What One Idle Hour Costs at Different Burn Rates and Prices
Find your burn rate down the side and your diesel price across the top
Each cell is gallons per hour times price per gallon. Prices are examples, so substitute your own current price.
| Burn rate | $3.00/gal | $3.50/gal | $4.00/gal | $4.50/gal |
|---|
| 0.6 gal/hr | $1.80 | $2.10 | $2.40 | $2.70 |
| 0.8 gal/hr | $2.40 | $2.80 | $3.20 | $3.60 |
| 1.0 gal/hr | $3.00 | $3.50 | $4.00 | $4.50 |
| 1.5 gal/hr | $4.50 | $5.25 | $6.00 | $6.75 |
What a year of idling costs, by idle hours and diesel price
This table uses Argonne's 0.8 gallons an hour. Argonne treats 1,000 hours a year as a low idler and 2,000 as a high idler.
| Idle hours a year | $3.00/gal | $3.50/gal | $4.00/gal | $4.50/gal |
|---|
| 1,000 idle hours | $2,400 | $2,800 | $3,200 | $3,600 |
| 1,800 idle hours | $4,320 | $5,040 | $5,760 | $6,480 |
| 2,000 idle hours | $4,800 | $5,600 | $6,400 | $7,200 |
Fuel is only part of the cost. Argonne notes idling accelerates engine wear, and where warranty and maintenance intervals run on hours instead of miles, idling costs more than fuel alone. It does not put a dollar figure on wear, and neither does this page, so add your own if you track it.
Not sure how many hours your trucks idle? Schedule a call and we will set up the tracking.
Idle hours per truck feed both the fuel math and engine-hour PM triggers.
Worked Example: A 50-Truck Fleet
At 1,800 idle hours a truck, a 20 percent cut is worth about $54,000 a year
Assumptions: 0.8 gallons an hour, $3.75 a gallon, 1,800 idle hours a truck a year, so 1,440 gallons and $5,400 per truck. For 50 trucks that is $270,000 a year. A 20 percent reduction saves $54,000, or $1,080 a truck. As a cross-check, the North American Council for Freight Efficiency (NACFE) estimates a 10 percent idle cut gives about $500 to $700 a year at $3 a gallon and 100,000 miles, which is the same order of magnitude as the $540 this example gives for 10 percent. Savings take time to arrive, so expect less in the first year.
| Line | Per truck | 50 trucks |
|---|
| Idle fuel a year | 1,440 gal | 72,000 gal |
| Idle fuel cost at $3.75 | $5,400 | $270,000 |
| Saved at 10% less idling | $540 | $27,000 |
| Saved at 20% less idling | $1,080 | $54,000 |
Idle-Reduction Options and How Fast They Pay Back
Cheap options pay back in under a year, and the expensive ones take three to five
The figures come from an Argonne fact sheet that draws its cost data from a 2014 NACFE report and assumes $3.00 a gallon and 1,800 idle hours a year. Equipment prices and paybacks have moved since, so treat them as a ranking and not a quote.
TYPICAL PAYBACK BY IDLE-REDUCTION OPTION, YEARS. ARGONNE, 2015, AT $3.00 A GALLON AND 1,800 HOURS
Diesel-fired heater
0.6 years
Heat recovery
Under 1 year
Auto engine start/stop
1 year
Electrified parking, dual
1 year
FUEL BURNED PER HOUR BY OPTION, GALLONS. ARGONNE, 2015
Diesel APU
0.2 - 0.5 gal/hr
Diesel-fired heater
0.04 - 0.08 gal/hr
Auto start/stop
0.25 gal/hr
Storage cooling
0.15 gal/hr
Idling the engine
0.6 - 1.5 gal/hr
Cheapest first
Fuel-operated heaters, engine idle settings and driver training have payback generally under a year, according to NACFE.
Higher capital, slower payback
APUs, battery HVAC, solar and start/stop can pay back in up to three years, with lower confidence.
Match to hours idled
Higher-capital options pay back faster on trucks that idle more. Low idlers may not recover cost within five years.
Checklist to Cut Idle Hours
Measure first, then fix the biggest idlers
NACFE has estimated that over-the-road tractors without idle-reduction tools could idle 40 to 50 percent of the time, and that fleets with programs run well below 20 percent. Both are estimates from a council executive, so find your own share.
Put a Number on Idling and Service Trucks by Engine Hours: Track Idle Cost and PM Intervals in FleetRabbit
FleetRabbit keeps PM schedules, inspections, work orders and costs for every vehicle in one record, so engine-hour services follow the hours a truck really ran, idle time included. Free for up to 3 vehicles, then $5 per vehicle per month.
PM by miles or engine hours
Cost per vehicle
Reminders before due
Free for 3 vehicles
Frequently Asked Questions
Quick answers on idle cost per hour
How much does idling cost per hour?
Gallons burned per hour times diesel price. At 0.8 gallons and $3.75 a gallon it is about $3.00, and at Argonne's range of 0.6 to 1.5 gallons it is about $2.25 to $5.63.
How much fuel does a truck burn idling?
About 0.8 gallons an hour on average, with a range of 0.6 to 1.5, according to Argonne National Laboratory.
How many hours do long-haul trucks idle?
About 1,800 hours a year on average, with low idlers near 1,000 and high idlers near 2,000, per Argonne.
Does idling damage the engine?
Argonne says it accelerates wear, but it does not quantify the cost. If your PM intervals run on engine hours, idle time counts toward them.
Which idle-reduction option pays back fastest?
Fuel-operated heaters, engine idle settings and driver training, at under a year in NACFE and Argonne figures. Equipment costs have changed since, so get current quotes.
How much can a fleet realistically cut?
NACFE calls a 20 percent reduction not unreasonable with the right mix of technology and management, though it is a projection.
What does FleetRabbit cost?
FleetRabbit is free for up to three vehicles and $5 per vehicle per month after that.
Track 3 vehicles free.
Stop Paying to Idle: Measure Hours, Cut the Worst, Service by Engine Hours
Idle time costs fuel and engine life. Track it per truck, set a target and keep PM intervals tied to the hours a truck really ran.
Free tier for up to 3 vehicles · No credit card required · Costs and hours stored per vehicle
October 17, 2026By Derek Goes
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