Fuel Cost Calculator

The fuel calculator answers the two questions every driver asks: how much a trip costs, and how far a budget will take you. Enter your car’s fuel economy (miles per gallon), the distance and the gas price per gallon — the calculator shows how much fuel you need and what it costs. Switch to the second mode, enter a budget instead of a distance, and see your range. The calculation is instant and runs on your device.

How to use the calculator

Pick a mode. “Trip cost” is the classic: fuel economy, distance, gas price — the result is gallons and dollars, plus the cost per mile for comparing cars and routes. “Range on a budget” is the reverse problem: how many miles a given amount buys. Enter fuel economy as an exact number (decimals work, like 27.4) or nudge it with the steppers. Units switch between miles + US gallons and kilometers + liters.

How the trip cost is calculated

The formula: fuel = distance ÷ fuel economy, cost = fuel × price per gallon. Example: 25 mpg over 200 miles at $3.50 per gallon takes 8 gallons (200 ÷ 25) and costs $28 (8 × $3.50). The reverse problem works through volume: the budget divided by the price per gallon gives gallons, and those gallons carry you distance equal to gallons × fuel economy.

What affects real fuel economy

The figure on the window sticker comes from lab tests; real-world results usually run 10–20% lower. Aggressive acceleration can add up to 15%, speeds above 70 mph raise consumption sharply, a roof box adds 5–15%, and underinflated tires, cold winter warm-ups and a poorly maintained engine all cost extra. For a personal figure: fill the tank, reset the trip odometer, drive 200–300 miles of your normal driving and fill up again — miles driven divided by gallons used gives your true mpg.

How to save fuel

Keep highway speed near 65–70 mph — every 5 mph above costs roughly 7% more fuel. Check tire pressure every couple of weeks. Take the roof box off when you are not using it. Every 100 lb of extra load adds about 1%. In winter, short trips never let the engine warm up, raising consumption 20–30% — combine errands into one run. Gas station apps show nearby prices: the difference between stations a block apart is often 20–30 cents per gallon.

This is an estimate. Actual fuel use depends on your car, the roads and your driving style.