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MPG calculator (fuel economy)

Compute miles per gallon and the equivalent L/100 km for your car.

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Need Fuel economy (MPG), Equivalent (L/100 km)? The MPG calculator (fuel economy) derives it from Distance (miles), Fuel used (US gallons) in one step. For instance, with Distance (miles) = 300 and Fuel used (US gallons) = 10 it returns Fuel economy (MPG) = 30 and Equivalent (L/100 km) = 7.841.

How to use it

  1. Enter your values: Distance (miles), Fuel used (US gallons).
  2. Read the result instantly: Fuel economy (MPG), Equivalent (L/100 km).

Frequently asked questions

What does the MPG calculator (fuel economy) actually compute?

It takes Distance (miles) and Fuel used (US gallons) and derives Fuel economy (MPG) and Equivalent (L/100 km) from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

2 values: Distance (miles) and Fuel used (US gallons). Nothing else is required — no account, no file upload.

Can you show a worked example?

With Distance (miles) = 300 and Fuel used (US gallons) = 10, the calculator returns Fuel economy (MPG) = 30 and Equivalent (L/100 km) = 7.841. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

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.

What is the difference between the MPG calculator (fuel economy) and the Fuel consumption calculator?

This one returns Fuel economy (MPG) and Equivalent (L/100 km); the Fuel consumption calculator returns Consumption (L/100 km) and Fuel cost. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Fuel cost calculator is the closest one after this: Estimate the fuel needed and its cost for a trip from distance and consumption.

What else is worth having open alongside it?

Fuel savings calculator and Fuel range calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from, and how current are they?

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 →
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.How-toFuel Cost for a Road TripDivide distance by fuel economy, then multiply by the price. Here's the calculation, metric vs mpg, what pushes it up, and how to split the cost.ComparisonLease vs Buy a CarLeasing means lower payments but no ownership; buying costs more per month but the car is yours. Here's how each works and which fits your situation.How-toHow Much Does It Cost to Charge an Electric Car?Charging cost is energy added times your electricity price. Here's the sum, home vs public charging, cost per 100 miles, and how it compares to gas.How-toThe Real Cost Per Mile of Driving: Beyond Just FuelFuel is only part of what a mile costs. Add depreciation, insurance and maintenance to find your true cost per mile — and why it is higher than the pump suggests.ExplainerThe Fuel Saving That Is Not LinearGoing from 10 to 20 mpg saves six times more fuel than going from 30 to 40, over the same distance. The reason is that fuel used is the reciprocal of fuel economy — and it changes which vehicle you should replace first.