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Miles per Gallon (MPG) Calculator

Calculate MPG, L/100 km and km/L, estimate trip fuel cost, and compare the running cost of two vehicles.

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Miles per Gallon (MPG) Calculator is free to use as often as you like, directly from this page. Its place is under Running costs; MPG calculator (fuel economy) and 0–60 / Quarter Mile Calculator answer the questions closest to this one.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Miles per Gallon (MPG) Calculator do?

Calculate MPG, L/100 km and km/L, estimate trip fuel cost, and compare the running cost of two vehicles.

When would I actually use this?

Deciding between two cars, or between keeping one and replacing it: fuel or charging, insurance, depreciation and what a kilometre really costs.

What is the most common mistake?

Comparing on fuel alone. Depreciation is usually the largest line in the first years and dwarfs the difference in consumption between two comparable cars.

How is Miles per Gallon (MPG) Calculator different from MPG calculator (fuel economy)?

They sit next to each other but answer different questions: MPG calculator (fuel economy) is the one to open when you need it to compute miles per gallon and the equivalent L/100 km for your car. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

0–60 / Quarter Mile Calculator is the closest one after this: Estimate 0–60 mph, quarter-mile ET and trap speed from power and weight using the Fox equation, with drivetrain and traction factors.

Where do the figures come from?

The arithmetic is exact for the prices and consumption you enter. Manufacturer figures are measured on a standard cycle and real-world consumption is routinely 10% to 25% higher.

Further reading

All guides →
ExplainerHeadlight Aim and How Far You Can Actually SeeA dipped beam is aimed downward by a fraction of a degree, so its reach on flat road is a single division. Do it and you find that at motorway speed the beam is shorter than the stopping distance — and that a loaded boot can throw the whole calculation away.ExplainerTongue Weight Is the Number That Stops a Trailer SwayingTowing limits tell you whether you may hitch up. Tongue weight tells you whether the combination will stay straight. It is set by where the trailer's centre of gravity sits relative to its axle, it moves faster than anyone expects, and the recommended bands are not the same on the two sides of the Atlantic.ExplainerWhere the Weight Sits Decides How the Car BehavesTwo axle weights and a wheelbase give you the exact position of a car's centre of gravity. From there the arithmetic keeps going: how much weight braking moves forward, why the rear axle is the one that runs out of grip, and why a load behind the rear axle takes weight off the front.ExplainerWhat Is MPG (and How to Improve It)?MPG is how far a car goes on a gallon — higher is better. Here's what it means, how it relates to L/100 km, why your real figure is lower, and how to improve it.GuideTowing Capacity: the Limit That Stops You FirstThere is no single towing capacity. There are four or five separate limits, and the one that binds is rarely the tow rating on the brochure — it is usually the vehicle's own weight budget, quietly consumed by the people sitting in it.ExplainerStopping Distance Is Mostly Not BrakingTotal stopping distance is two distances added together, and they follow different laws — one grows with speed, the other with speed squared. That single fact explains why doubling your speed roughly triples the distance.