Towing Trip Fuel Calculator (MPG Loss)
Estimate the extra fuel and cost of towing on a trip by applying a fuel-economy penalty to your unloaded MPG over the trip distance.
How it works
Towing MPG = base MPG × (1 − penalty%) · Fuel = distance ÷ towing MPG · Extra = towing fuel − solo fuel
A trailer’s frontal area and weight drag your fuel economy down by a fraction that is fairly consistent for a given rig — often 25–50% for a large travel trailer. Apply that penalty to your normal MPG to get an effective towing MPG, then divide the trip distance by it for the fuel used; the gap versus your solo consumption is the true cost of towing. Aerodynamic drag dominates at highway speed, so a tall, boxy trailer hurts economy far more than a low, sleek one of the same weight.
Worked example
At 20 mpg solo with a 35% towing penalty, effective economy is 20 × 0.65 = 13 mpg. A 400-mile trip then burns 400 ÷ 13 ≈ 30.8 gal versus 20 gal solo — about 10.8 extra gallons for the tow.
Frequently asked questions
How much does towing reduce fuel economy?
It varies with weight, size and speed, but a large travel trailer commonly cuts MPG by 25–50%, and a tall, boxy trailer at highway speed can be worse. A small, aerodynamic trailer might cost only 10–20%. Use your own observed penalty for the best estimate.
Why does towing hurt MPG so much?
Mostly aerodynamic drag. Pulling a large frontal area through the air at highway speed takes far more energy, and the added weight increases rolling resistance and the work of climbing grades and accelerating. Slowing down a few mph noticeably helps.
How can I improve fuel economy while towing?
Slow down, keep tires at the correct pressure, avoid unnecessary weight, and choose a more aerodynamic trailer where you can. Steady speeds and gentle acceleration also help since drag and hard pulls are where the fuel goes.
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This calculator is for educational purposes. Double-check important results before acting on them.