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MPG / Gas Mileage Calculator

Compute your fuel economy from a fill-up: miles driven ÷ gallons used. Average several fill-ups, switch to UK gallons or metric, or work out how far a tank will take you.

Instant results Private — runs in your browser Updated October 2026

Inputs

Units

Mode

Miles driven since last fill-up

Gallons to refill

gal

Fuel price$/gallon

Fuel economy

29.17 mpg

8.1 L/100 km

Cost per mile

$0.12

Annual fuel cost (15k mi)

$1,800.00

MPG

29.17 mpg

Rough guide: the US new-car fleet average is about 27.5 mpg. Above 30 mpg is good, above 40 is very good, and hybrids often reach 50–60 mpg. Trucks and SUVs are typically judged on a lower scale — 22–25 mpg is good for that class.

How it works

Single fill-up: fuel economy = distance ÷ fuel used. Cost per mile = fuel price ÷ economy, and the annual estimate assumes 15,000 miles per year (24,000 km in metric mode).

Multi fill-up averaging totals every entered distance and every entered volume, then divides — so longer tanks correctly carry more weight than short ones. Each tank's own figure is listed and charted beside the others so you can see the spread.

Units are applied at the source, not converted afterwards. US mode uses miles ÷ US gallons, UK mode uses miles ÷ Imperial gallons (1 UK gal = 1.20095 US gal), and metric mode computes km per litre directly, with L/100 km shown as 100 ÷ km-per-litre. Range mode multiplies your economy by the fuel available, in whichever unit system is selected.

Frequently asked questions

Why does my MPG vary between fill-ups?

Cold starts, short trips, stop-and-go traffic, headwinds, roof racks, low tire pressure, extra cargo and aggressive acceleration all move the number. A 3–5 mpg swing between consecutive tanks is completely normal, which is why a single tank is a weak measurement.

What's the most accurate way to measure fuel economy?

Track 3–5 consecutive fill-ups, always filling to the same click-off point at the same pump, and divide total distance by total fuel used. That's what the multi fill-up mode here does — it totals distance and fuel rather than averaging the individual tank figures, which is the mathematically correct way.

Should I use my trip meter or odometer?

Either works if you're consistent. The trip meter is easier — reset it at every fill-up. The odometer is slightly more reliable over long periods because you can't accidentally reset it mid-tank. Note that many trip meters read 1–3% optimistic, so your true economy may be a touch lower.

What's a good MPG for my vehicle type?

Compacts and sedans: 30–40 mpg is good. Hybrids: 50–60 mpg. Crossovers: 26–30 mpg. Trucks and large SUVs: 22–25 mpg is good for the class. The US new-car fleet average sits around 27.5 mpg, so judge your vehicle against its own class rather than the overall average.

Why is my highway MPG different from city MPG?

In city driving you spend energy accelerating from a stop and then throw it away as heat when braking, and you idle at lights. On the highway the engine runs at a steady, efficient load. Above roughly 60 mph aerodynamic drag starts dominating, so very high speeds cut highway economy again.

What's the difference between US and UK gallons?

An Imperial (UK) gallon is about 20% larger than a US gallon — 1 UK gallon = 1.20095 US gallons (4.546 L vs 3.785 L). The same car therefore shows a higher mpg figure in the UK. Divide a UK mpg figure by 1.20095 to get the US equivalent, which is why the units toggle matters here.

Are the EPA numbers realistic?

The EPA numbers are lab-tested. Real-world economy usually lands 10–20% below the sticker.