Fuel Cost Calculator — Trip Cost From Distance and MPG

Fuel Cost Calculator

Enter a distance, your fuel efficiency and the price per unit to see what a trip costs — and the cost per person if you split it.

The calculation

Fuel cost is distance divided by efficiency, times the price per unit. In US units: miles ÷ MPG gives gallons, times the price per gallon. In metric: distance ÷ 100 × L/100km gives litres, times the price per litre. Both are handled here — just pick the units your dashboard and pump use.

MPG and L/100km run in opposite directions

This confuses people who switch between systems. With MPG, higher is better — more miles per gallon. With L/100km, lower is better — fewer litres to cover the same distance. A car doing 30 MPG uses about 7.8 L/100km. Do not compare the two numbers directly; convert first or use the matching unit.

Real-world figures beat the sticker

Manufacturer efficiency figures are measured in ideal conditions. Real driving is worse, sometimes by 10% to 30%, because of cold starts, headwinds, roof boxes, air conditioning, a heavy right foot and stop-start traffic. For a trip you actually want to budget for, use the efficiency you observe on your own fill-ups rather than the brochure number.

Splitting and round trips

The per-person figure makes carpooling easy to settle, and the round-trip line saves you doubling in your head. For a fair split, divide the total fuel cost by the number of people in the car, driver included — or let the per-person figure above do it. To split a meal the same way, the tip calculator handles the bill and the gratuity.

Frequently asked questions

How do I calculate fuel cost for a trip?

Divide the distance by your fuel efficiency to get the fuel used, then multiply by the price per gallon or litre. The calculator does both unit systems for you.

What is a good MPG or L/100km figure?

It depends on the vehicle, but a modern petrol car often does 30 to 45 MPG (about 5 to 8 L/100km). Hybrids do better; large SUVs and trucks do considerably worse.

Why does my real fuel use exceed the official figure?

Official figures come from controlled tests. Cold weather, short journeys, high speeds, air conditioning and aggressive acceleration all raise real consumption, sometimes by a third.

How do I convert MPG to L/100km?

Divide 235.2 by the MPG figure. So 30 MPG is about 7.8 L/100km. Remember the two scales move in opposite directions — high MPG is good, low L/100km is good.