Fuel Cost Calculator
Estimate the fuel cost of a trip from distance, efficiency and fuel price.
About Fuel Cost Calculator
In imperial units, fuel used equals distance divided by miles-per-gallon; in metric, it's the distance in hundreds of kilometers times your L/100km figure. Multiply by fuel price for the total trip cost.
Formulas
Imperial (MPG)
Fuel (gal) = Distance (mi) ÷ MPG Cost = Fuel × price per gallon
- d
- Trip distance in miles
- MPG
- Miles per gallon fuel efficiency
- p
- Price per gallon
Metric (L/100 km)
Fuel (L) = (Distance (km) ÷ 100) × L/100km Cost = Fuel × price per litre
- d
- Trip distance in kilometres
- L/100km
- Fuel consumption in litres per 100 km
- p
- Price per litre
Worked example
With the default values below, Fuel Cost Calculator returns Total Fuel Cost of $35.00. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Unitsone of Imperial (miles, MPG, $/gallon), Metric (km, L/100km, $/liter)
- Imperial (miles, MPG, $/gallon)
- Trip Distanceaccepts 0–100,000 mi / km
- 300 mi / km
- Fuel Efficiencyaccepts 0.1–200 MPG / L·100km
- 30 MPG / L·100km
- Fuel Priceaccepts 0–100 $
- 3.5 $
Results
- Total Fuel Cost
- $35.00
- Fuel Used (gal / L)
- 10.00
- Cost per Mile / km
- $0.117
Step by step
- 1Calculate fuel used (distance ÷ MPG)= 10.00 gal
- 2Multiply fuel used by price per gal= $35.00
- 3Cost per mi= $0.117/mi
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Fuel Cost Calculator — full guide
Before you book the drive
Two cars, two routes, or driving versus flying — the comparison only becomes concrete once the trip has a price on it. This calculator turns a distance, a consumption figure and a pump price into the total fuel bill, the volume of fuel burned, and a cost per mile or kilometre you can reuse for mileage claims and quotes.
Imperial and metric work in opposite directions
Pick the Units option that matches how your car reports consumption, because the two systems are reciprocal and are not interchangeable.
Imperial — miles per gallon, where higher is better:
Fuel (gal) = Distance (mi) ÷ MPG, then Cost = Fuel × price per gallon
Metric — litres per 100 km, where lower is better:
Fuel (L) = (Distance (km) ÷ 100) × L/100km, then Cost = Fuel × price per litre
In both cases the Fuel Price field must be the price for the same volume unit the system uses: per gallon in imperial, per litre in metric.
The default trip
Imperial units, 300 miles, 30 MPG, fuel at 3.50 per gallon:
- Fuel used: 300 ÷ 30 = 10 gallons.
- Total cost: 10 × 3.50 = 35.00.
- Cost per mile: 35.00 ÷ 300 = 0.1167, just under 12 cents a mile.
The metric path with real numbers: a 480 km drive at 7.5 L/100km with fuel at 1.60 per litre burns (480 ÷ 100) × 7.5 = 36 L, costs 36 × 1.60 = 57.60, and works out at 0.12 per kilometre.
What the cost per mile is for
It is the number worth remembering, because it scales. At 0.1167 per mile, a 40 mile daily commute costs about 4.67 in fuel, and 1,200 miles a month costs 140.
Efficiency moves the bill more than most drivers expect. Same 300 mile trip, same 3.50 fuel:
| MPG | Gallons | Trip cost |
|---|---|---|
| 24 | 12.50 | 43.75 |
| 30 | 10.00 | 35.00 |
| 36 | 8.33 | 29.17 |
| 45 | 6.67 | 23.33 |
Dropping from 30 to 24 MPG — roughly what a roof box, cold weather and motorway speeds can do together — adds 8.75, a 25% increase on the same journey.
Assumptions to keep in mind
- Enter the full distance you will drive. A 300 mile destination means 600 miles entered for a return trip, and 70.00 of fuel.
- The manufacturer's rating is usually optimistic. Use your trip computer's long-term average, or the pump-to-pump figure you worked out yourself.
- This is fuel only. Tolls, parking, tyres and servicing are real costs per mile and are not included here.
- Fuel prices move weekly and vary between stations, so the total is only as current as the price you typed.
Converting a distance or a consumption figure between systems? Use the unit converter. To see the percentage gap between two cars' running costs, use the percentage increase calculator, and for the other large cost of ownership see the auto loan calculator.
Frequently Asked Questions
Where do I find my fuel efficiency?
Check your vehicle's trip computer or manufacturer rating. In the U.S. it's miles per gallon (MPG); in much of the world it's liters per 100 km.
Can I estimate a round trip?
Yes — just enter the total distance for the whole journey, including the return leg.
My car shows L/100km but fuel is sold by the gallon where I'm driving — what do I enter?
Keep the system and the price unit matched. Either switch to metric and convert the pump price to a price per litre, or stay imperial and convert your consumption: 7.84 L/100km is about 30 MPG. Mixing a litre-based price with an MPG figure silently produces a wrong total.
How much does the pump price actually swing the trip cost?
Strictly in proportion, because fuel used does not change. The default 300 mile trip at 30 MPG burns 10 gallons, so every 0.10 on the pump price adds 1.00. Going from 3.50 to 4.25 per gallon raises the trip from 35.00 to 42.50 — a 21.4% rise.
Can I use the cost per mile to compare two different routes?
Compare the total cost, not the cost per mile. A 300 mile motorway run at 30 MPG costs 35.00 at 0.1167 per mile; a 340 mile route where steadier driving yields 35 MPG costs 34.00 at 0.10 per mile. The longer route is cheaper despite being 40 miles further.
Does this work for a hybrid or an electric car?
For a hybrid, yes — enter the combined MPG or L/100km your trip computer reports, since the calculator only cares about fuel actually burned. For a fully electric car there is no fuel volume or pump price to enter, so the maths does not apply; price electricity in kWh instead.