MPG calculator

Type miles and gallons in measure mode. The calculator divides miles by gallons: 250 miles and 10 gallons give 25 mpg. That is tank economy, not a window sticker. With the metric header the same figure is also shown as L/100 km.

Measure economy, then paste the result into trip fuel cost. The year lives on annual running cost, the full picture on car TCO.

Input data

Mode
Optional

Results

Distance and fuel added, or distance and known economy. Consumption shows up here.

How the results are calculated

In measure mode, consumption is fuel added divided by distance, times 100. 500 km and 32 L give 6.4 L/100 km. 800 km and 48 L give 6.0. 300 km and 27 L give 9.0, typical city traffic. The same pair in km/L is 100 divided by L/100 km: 6.4 L/100 km is about 15.63 km/L.

Estimate mode flips the question: you know economy and distance, and you want liters for the trip. 420 km at 6.5 L/100 km is 27.3 L. Fuel price and annual distance are optional: at 6.39 per liter that stretch is about 174.45, and the city / mixed / highway chart is only an order of magnitude for the year.

Measure fields are distance and fuel added. Estimate fields are distance and known consumption. The US header relabels to miles and gallons: then mpg is miles divided by gallons. A typed 500 is not multiplied by 0.621. A comma and a period in 6.5 are the same economy figure.

One trip in money lives on trip fuel cost. A year of service, insurance, and tires lives on annual running cost. Here it stays tank economy or an assumed L/100 km. A type-approval sticker is a lab cycle, not this measurement.

Typed zero kilometers cannot divide, because there is no stretch. A blank distance field does not fill 500 from the example. A minus is rejected as a typing slip. A tank-to-tank reading is closer to daily driving than a catalog, and it is still an estimate from one fill-up.

Type 500 and 32, click Calculate, and match 6.4 L/100 km. Then 32.5 L on 500 km: you get 6.5. Paste that number into trip fuel cost when you want money on a route, not liters per hundred.

How to use

  1. Pick measure (distance + fuel added) or estimate (distance + known economy).
  2. In measure mode, type miles and gallons, for example 250 miles and 10 gallons.
  3. Click Calculate. 250 and 10 give 25 mpg. 320 and 10 give 32 mpg.
  4. Optionally add fuel price and annual distance to see stretch cost and the driving-style chart.
  5. Paste the result into trip fuel cost. Here it stays economy, not TCO.

mpg from the tank, not trip cost

Miles ÷ gallons. 250 miles and 10 gallons give 25 mpg. 320 miles and 10 gallons give 32 mpg. Tank economy, not TCO.

mpg
The measure-mode result with the US header. 250 / 10 = 25. 180 / 10 = 18 in city traffic. The metric header reports L/100 km and still shows the mpg equivalent.
Fuel
Gallons added on that stretch. 10 gallons over 250 miles is 25 mpg. Price is an optional cost line, not a separate TCO.

Using this motoring calculator

  1. Measure economy from a real fill-up (distance + fuel added), or estimate it from a known consumption figure.
  2. Switch result units (L/100 km, km/L, mpg) without reloading the page.
  3. Add fuel price and annual distance if you want to see how driving style changes your yearly fuel spend.
  4. Carry the number into trip fuel cost or annual running cost.

Examples

Example 1

  • Mode: measure
  • 500
  • 32 of fuel

36.8 mpg

How many mpg at 500 km and 32 L?

Example 2

  • Mode: measure
  • 800
  • 48 of fuel

39.2 mpg

How many mpg at 800 km and 48 L?

Example 3

  • Mode: measure
  • 300
  • 27 of fuel

26.1 mpg

How many mpg at 300 km and 27 L?

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Frequently asked questions

How many L/100 km at 500 km and 32 L?

32 / 500 × 100 = 6.4 L/100 km. At 32.5 L on the same 500 km you get 6.5.

How is measure different from estimate?

Measure divides fuel added by distance. Estimate multiplies known economy by distance to size liters for a trip.

How many mpg is 6.4 L/100 km?

235.215 / 6.4 ≈ 36.8 mpg, and 100 / 6.4 ≈ 15.63 km/L. With the US header the same economy is computed from miles and gallons.

Does 6.4 replace a type-approval sticker?

No. The sticker is a lab cycle. Here you compute a tank stretch. It is an estimate from your numbers, not a certificate.

What are price and annual distance for?

Price multiplies liters on the stretch. Annual distance feeds the city / mixed / highway chart. Both fields are optional.

Does the US switch convert a typed 500 km?

No. On an empty field it relabels to miles. It does not convert a number you already typed.

What if distance is blank?

The calculator does not compute and does not fill 500 from the example. Measure needs kilometers and liters.

Does a comma in 6.5 work?

Yes. 6,5 and 6.5 are the same economy in estimate mode.

How much fuel for 420 km at 6.5 L/100 km?

420 × 6.5 / 100 = 27.3 L. At 6.39 per liter that is about 174.45 if you add a price.

Where do I get money for the trip?

On trip fuel cost. The year of upkeep is annual running cost. Here you stay with L/100 km or mpg.

Knowledge sources

Use and cost come from your own numbers. Below is the FuelEconomy.gov and EPA vocabulary.

Page updated in 2026.