Free Trucking Tool
Truck MPG Calculator: Free Fuel Economy Tool
Get your exact miles-per-gallon, fuel cost per mile, and annual fuel cost — all from two numbers: miles driven and gallons used. No signup, no email.
Quick Answer
Truck MPG = miles driven ÷ gallons used. Fill the tank full, reset the trip odometer, drive, then refill and divide the miles by the gallons added. Example: 1,200 miles ÷ 200 gallons = 6.0 MPG. This calculator also returns your fuel cost per mile and annual fuel cost projection from those same two numbers.
Key Takeaways
- The formula is simple: MPG = miles driven ÷ gallons used.
- For an accurate reading, fill the tank completely, reset the trip odometer, then refill to full and use the exact gallons added.
- Average 3–5 fill-ups in similar conditions — a single tank can be misleading after mountain pulls, traffic, or a heavy payload.
- Class 8 over-the-road trucks average 6.0–6.5 MPG loaded and 7.5+ MPG empty (bobtail).
- Slowing down is the biggest lever — every 1 MPH above 65 costs roughly 0.1 MPG.
- Winter MPG typically drops 10–15% from cold-air drag, winter-blend diesel, and extra idling.
O TruckingMPG Calculator
Truck MPG Calculator
Trip odometer reading or hub-meter delta between fill-ups.
Total gallons added at the pump to top off.
National diesel avg as of May 2026: ~$3.78/gal.
How to Use This MPG Calculator
- 1At your next fill-up, fill the tank completely to the top and reset your trip odometer (or note the hub-meter reading).
- 2Drive as you normally would, ideally until the tank is at least half-empty for an accurate average.
- 3At the next fill-up, top the tank back to full and note the exact gallons added.
- 4Enter the miles driven (trip odometer) and gallons added into the calculator above. Your MPG appears instantly.
For most accurate results: average 3–5 fill-ups in similar conditions (same lane, similar weather, similar load weight). A single tank can be misleading if you ran a lot of mountain pulls, sat in traffic, or had a heavier-than-usual payload.
MPG Calculator FAQ
How do I calculate MPG for my truck?▼
MPG = Miles Driven ÷ Gallons Used. Reset your trip odometer at one fill-up, drive until empty or near-empty, then fill the tank completely at the next stop. Divide the miles since reset by the gallons you just put in. Example: 1,200 miles ÷ 200 gallons = 6.0 MPG.
What's a good MPG for a class 8 truck?▼
Class 8 over-the-road trucks average 6.0–6.5 MPG loaded and 7.5+ MPG empty (bobtail). Modern 2020+ tractors with aerodynamic packages and APUs average 7.0–7.5 MPG combined. The North American Council for Freight Efficiency (NACFE) tracks fleet leaders running 8.5–10.0 MPG with extensive aero retrofits. Below 5.5 MPG loaded usually points to tire pressure, excessive idling, or aggressive driving.
How can I improve my truck's MPG?▼
Proven gains, ranked by impact: (1) Slow down — every 1 MPH above 65 costs roughly 0.1 MPG. Dropping from 68 to 62 saves 3–6%. (2) Tire pressure — under-inflation by 10 PSI costs 1–3% fuel. (3) Reduce idle time — an APU saves $5,000–$9,000/year on a long-haul truck. (4) Progressive shifting — short-shift through the lower gears, target 1,250–1,400 RPM in cruise. (5) Aero retrofits — skirts, tail fairings, gap reducers save 6–12% combined. Avoid 'fuel additives' and bolt-on miracle devices — independent testing shows zero meaningful gain.
How much does poor MPG actually cost me per year?▼
At 100,000 miles/year and $3.80/gal diesel: 6.0 MPG costs $63,333/year in fuel. 6.5 MPG costs $58,462. 7.0 MPG costs $54,286. The difference between 6.0 and 7.0 MPG is $9,047/year — about three months of truck payments. The calculator above shows your exact annual cost and savings projection.
Why does my MPG drop in winter?▼
Winter MPG typically drops 10–15% due to: (1) denser cold air increasing aerodynamic drag, (2) diesel switching to winter blend (3–5% lower BTU/gallon), (3) more idling for cab heat, (4) underinflated tires from cold-weather PSI drops, (5) increased rolling resistance on snow and salted roads. If your MPG drops more than 15% in winter, check for excessive idling or low tire pressure.
Does payload weight affect MPG?▼
Yes, significantly. Every 1,000 lbs of additional weight costs roughly 0.05–0.1 MPG on long hauls. A truck running at 80,000 lbs GVW will burn 6–8% more fuel than one running at 60,000 lbs over the same lane. This is why deadhead empty miles (~7.5 MPG) cost less than loaded miles (~6.0 MPG) even though they don't pay.
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