Fuel & DEF Verified Factory Specs

Commercial Heavy Truck Fuel Consumption Calculator (GPH & MPG)

Calculate commercial heavy duty diesel fuel burn rate in Gallons Per Hour (GPH), Miles Per Gallon (MPG), and total trip fuel burn based on engine horsepower and load factor.

Engine Rated Horsepower (HP)

Average Engine Load Factor

Average Cruise Speed

MPH

SCR DEF Dosing Rate

Fuel Burn Rate (GPH)

10.57 gal/hr

40.01 Liters/hour

Calculated Fuel Mileage

6.1 MPG

At 65 MPH sustained cruise

DEF Injection Rate

0.317 gal/hr

3% of diesel consumption

DEF Range Per Gallon

205 miles/gal

~3075 miles on 15-gal tank

Commercial Truck Fuel Consumption Mathematics

Heavy diesel fuel consumption is governed by the engine power demand and Brake Specific Fuel Consumption (BSFC):

Fuel Burn Rate (GPH) = (Rated HP × Load Factor × BSFC) ÷ 7.10 lbs/gal

For example, a 500 HP engine cruising at 50% average load with a BSFC of 0.330 lb/hp·hr burns:
(500 × 0.50 × 0.330) ÷ 7.10 = 11.62 Gallons Per Hour (GPH). At 65 MPH, this equates to 65 ÷ 11.62 = 5.59 MPG.

Related Heavy Diesel Engineering Tools

Cross-reference other factory specifications and diagnostic tools for commercial diesel engines:

Pillar 3 →

Valve Lash & Overhead

Intake, exhaust, & Jake brake clearances.

Pillar 1 →

Oil & Coolant Sump

Standard vs deep pan fill volumes.

Pillar 4 →

Head Bolt Torque

Torque-to-yield angle stages & sequences.

Pillar 2 →

SPN Fault Code Lookup

J1939 fault diagnostics & sensor pins.

Technical Reference Citation: SAE J1321 Type II Fuel Economy Test Procedures

View Engineering Methodology & Standards →