What does the Gas Mileage Calculator compute?

It converts a trip's distance and fuel used into MPG (miles per gallon), L/100km (liters per 100 kilometers), and km/L (kilometers per liter) all at once, so you can compare figures however they're reported.

Can I mix miles with liters in the Gas Mileage Calculator?

Yes. Distance and fuel each have their own unit toggle, so you can enter miles with liters or kilometers with gallons — the calculator converts everything internally before computing MPG, L/100km, and km/L.

Why does a lower L/100km number mean better fuel economy?

L/100km measures fuel consumed per fixed distance, so a smaller number means less fuel was needed to cover the same 100 km — the opposite direction from MPG and km/L, which increase as economy improves.

Does the Gas Mileage Calculator use US or imperial gallons?

It uses the US gallon (3.785411784 liters). If your numbers come from a country using imperial gallons, convert to liters before entering them for an accurate MPG figure.

Does the Gas Mileage Calculator upload my trip data?

No. The Gas Mileage Calculator runs entirely in your browser. The distance and fuel figures you type never leave your device and are not uploaded to ArrayKit.

How accurate is the MPG figure from this calculator?

The math is exact for the numbers you enter, but real-world fuel economy varies with driving style, terrain, and weather — treat the result as an estimate and verify against your vehicle's own fill-up records before relying on it for budgeting.

Gas Mileage Calculator Online

Work out MPG, L/100km, and km/L from a trip's distance and fuel used, in your browser. Your figures stay on your device.

The Gas Mileage Calculator runs entirely in your browser. The distance and fuel figures you enter never leave your device and nothing is uploaded to ArrayKit.

Open the Fuel Cost Calculator

About Gas Mileage Calculator

The Gas Mileage Calculator turns a trip's distance and fuel used into three common fuel-economy figures: miles per gallon (MPG), liters per 100 kilometers (L/100km), and kilometers per liter (km/L). Enter distance in miles or kilometers and fuel used in gallons or liters — any combination works, since the calculator converts internally before computing every figure. It is handy for comparing a car's real-world economy against the window sticker, tracking mileage across a road trip logged in mixed units, or converting a spec sheet from one country's units to another. Built for drivers, fleet managers, and shoppers comparing vehicles across regions. Figures are estimates for comparison — actual fuel economy varies with driving conditions, so verify against your vehicle's own trip records before relying on it for budgeting. Everything runs locally in your browser; nothing you type is uploaded.

Features

Computes MPG, L/100km, and km/L from a single distance and fuel entry
Distance toggle accepts miles or kilometers
Fuel toggle accepts US gallons or liters
Mix any distance unit with any fuel unit — conversion happens automatically
Copy a plain-text summary of all three results at once
Clear error message when distance or fuel is missing or zero
Live results update as you type, no submit button needed
Runs entirely in your browser with no trip data sent anywhere

How to use the Gas Mileage Calculator

Choose your distance unit (miles or kilometers) and enter the trip distance
Choose your fuel unit (gallons or liters) and enter the fuel used
Read MPG, L/100km, and km/L in the results panel
Copy the summary to save or share your fuel-economy figures

Example

Input

300 mi, 10 gal

Output

30 MPG (7.84 L/100km)

300 miles on 10 gallons is 30 MPG, which converts to about 7.84 L/100km.

Common errors & troubleshooting

MPG and L/100km results look inconsistent with each other. — Remember MPG and km/L go up as economy improves, while L/100km goes down for the same improvement — they measure economy in opposite directions, not a calculation error.
Result shows 0 for every figure. — Distance and fuel used must both be greater than 0. Check that neither field was left blank or entered as a negative number.
Numbers don't match the car's dashboard readout. — Onboard trip computers estimate live consumption and can drift from a true fill-to-fill calculation; use a full tank-to-tank distance and fuel amount here for the most accurate comparison.
Mixing up US gallons with imperial gallons. — This calculator uses the US gallon (3.785 liters). If your fuel receipt uses imperial gallons (4.546 liters), convert to liters first for an accurate result.

Frequently asked questions

What does the Gas Mileage Calculator compute?: It converts a trip's distance and fuel used into MPG (miles per gallon), L/100km (liters per 100 kilometers), and km/L (kilometers per liter) all at once, so you can compare figures however they're reported.
Can I mix miles with liters in the Gas Mileage Calculator?: Yes. Distance and fuel each have their own unit toggle, so you can enter miles with liters or kilometers with gallons — the calculator converts everything internally before computing MPG, L/100km, and km/L.
Why does a lower L/100km number mean better fuel economy?: L/100km measures fuel consumed per fixed distance, so a smaller number means less fuel was needed to cover the same 100 km — the opposite direction from MPG and km/L, which increase as economy improves.
Does the Gas Mileage Calculator use US or imperial gallons?: It uses the US gallon (3.785411784 liters). If your numbers come from a country using imperial gallons, convert to liters before entering them for an accurate MPG figure.
Does the Gas Mileage Calculator upload my trip data?: No. The Gas Mileage Calculator runs entirely in your browser. The distance and fuel figures you type never leave your device and are not uploaded to ArrayKit.
How accurate is the MPG figure from this calculator?: The math is exact for the numbers you enter, but real-world fuel economy varies with driving style, terrain, and weather — treat the result as an estimate and verify against your vehicle's own fill-up records before relying on it for budgeting.

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