Distance to Empty Calculator: Range on a Tank
How far can I drive on a tank of fuel? Enter your fuel economy, the tank size and the fuel left to see the distance per full tank and your distance to empty. It works in US mpg, UK mpg and L/100 km. To work out what the trip costs, use the fuel cost calculator, and to find your economy first, use the MPG calculator.
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Formula
range = fuel × economy with mpg, or range = fuel ÷ L/100 km × 100 with litres per 100 km.
Constants: 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L. Distance to empty uses the fuel left instead of the tank size.
Worked example
30 mpg (US), 15 gallon tank, 5 gallons left: full range 30 × 15 = 450 miles (724.2 km); distance to empty 30 × 5 = 150 miles (241.4 km).
At 8 L/100 km with a 50 L tank: 50 ÷ 8 × 100 = 625 km.
Use this when
You want to know whether you can reach the next fuel stop, how far a full tank should take you, or how much safety margin the fuel gauge leaves. It is a planning figure: the tank size and the fuel left are numbers you enter, not something the car reports.
Typical values
Typical petrol cars consume roughly 5 to 10 L/100 km, which is roughly 24 to 47 US mpg, and typical tanks hold roughly 40 to 70 litres (about 10.5 to 18.5 US gallons). Your own car may differ.
How it differs from nearby pages
The MPG calculator finds your fuel economy from distance and fuel used. This page uses that economy to find a distance. The fuel cost calculator turns distance into money, and the average speed calculator is about time rather than fuel.
Common mistakes
- Mixing US and UK gallons. The mpg and tank size must use the same gallon.
- Using the brochure figure instead of your recent average.
- Running the tank right down to zero. Hills, speed, cold weather and heavy loads all cut the real range.
- Forgetting that L/100 km is the reverse of mpg: lower is better.
Frequently asked questions
How do I work out the range of a full tank?
Multiply fuel economy by tank size. A 15 US gallon tank at 30 mpg gives 450 miles, which is 724 km. With L/100 km, divide tank litres by the economy and multiply by 100: 50 L at 8 L/100 km is 625 km.
Why do US and UK mpg give different answers?
A UK gallon is 4.54609 litres and a US gallon is 3.785411784 litres, so 40 UK mpg is about 33.3 US mpg. The tank size must be in the same gallons as the mpg.
Is the distance to empty exact?
No. It assumes your economy stays constant. Hills, speed, cold weather and heavy loads can cut it, so treat the figure as a guide and refuel before the tank is nearly empty.
What economy should I use?
Use the average over your last few full tanks rather than the brochure figure. Divide the distance driven by the fuel added at the pump when you fill to full each time.
How many miles can I drive on 3 gallons?
Multiply gallons by mpg. At 25 mpg (US) a tank with 3 gallons left gives 75 miles, which is 120.7 km. An 18 gallon tank at the same economy is 450 miles on a full tank.
How do I find range from L/100 km and litres?
Divide litres by the consumption and multiply by 100. A 50 L tank at 6.5 L/100 km goes 769.2 km (478 miles) on a full tank, and 8 L left gives 123.1 km (76.5 miles).
What is the distance to empty with UK mpg?
UK gallons are larger, 4.54609 L, so the tank must be entered in UK gallons too. A 12 UK gallon tank at 45 mpg goes 540 miles (869 km), and 2 gallons left is 90 miles (144.8 km).