🚗 Cost Per Mile Calculator: Fuel and Driving Cost Per Mile
By Shihab Mia · Reviewed by ToolNimba Editorial Review, personal finance content · Updated 2026-07-03
This calculator gives an estimate only. Your real cost per mile depends on live fuel prices, your actual fuel economy in mixed driving, and costs this tool does not include such as insurance, depreciation, tyres and finance. Treat the figure as a guide, not financial advice, and confirm rates with your own records before billing or budgeting.
This cost per mile calculator works out how much each mile of driving actually costs you. Enter your fuel price and your vehicle fuel economy and it instantly returns the fuel cost per mile. Add an optional maintenance figure to get a fuller total cost per mile, then enter a trip distance to see what a specific journey costs. Switch between US units (price per gallon and MPG) and metric units (price per litre and L/100km) with one tap, and read the result to the cent.
What is the Cost Per Mile Calculator?
Cost per mile is simply what it costs to move your vehicle one mile. The largest variable cost is usually fuel, and the fuel part is easy to work out: divide the price you pay for a unit of fuel by how far that unit takes you. In US units that is fuel price per gallon divided by miles per gallon (MPG). A car doing 30 MPG on $3.50 fuel costs 3.50 / 30 = about $0.117 per mile in fuel, which is exactly what this cost per mile calculator returns when you enter those two numbers.
Metric figures need one extra step because economy is quoted as litres per 100 km (L/100km) rather than distance per unit. Cost per kilometre is price per litre times L/100km divided by 100. To compare like for like with US numbers, the tool then converts kilometres to miles using 1 km = 0.621371 miles. Lower L/100km means a more efficient car, the opposite direction to MPG where higher is better, which is a common source of confusion when comparing vehicles across regions. Getting your driving cost per mile right starts with entering the correct unit.
Fuel is not the whole story. Running a vehicle also wears out tyres, brakes, oil and other parts, and serious cost per mile figures used by fleets and the self-employed add a maintenance allowance per mile on top of fuel. This calculator lets you add that figure so the total reflects more than the pump price. Bigger ownership costs like insurance, depreciation and finance are not per-mile in the same way, so they are left out here, but it is worth remembering they push the true cost of motoring well above the fuel-plus-maintenance number.
Why does the fuel cost per mile matter so much? Because small differences compound over a year. A driver covering 12,000 miles at $0.15 per mile spends about $1,800 on fuel, while the same distance at $0.10 per mile costs $1,200. That $600 gap is the difference a more efficient car, a lower pump price, or a smoother driving style can make. Running your own numbers through a mileage cost calculator turns an abstract worry about petrol prices into a figure you can plan around.
The same maths powers a trip fuel cost calculator. Once you know the total cost per mile, multiply it by the distance of any journey to get the trip cost. This is what lets you compare driving against the train, a flight, or a rideshare, or split a road trip fairly between passengers. It is also the basis for setting a fair mileage rate if you charge clients for travel: work out your real gas cost per mile, add maintenance, and you have a defensible per-mile figure rather than a guess.
Finally, remember that a cost per mile is a snapshot. Fuel prices move week to week and your economy changes with the seasons, your load and your route. The cost per mile formula never changes, but the inputs do, so it is worth rechecking your car cost per mile whenever prices swing or before you rely on the number for budgeting or billing.
When to use it
- Working out the fuel cost of a specific trip before you set off, so you can budget or split it fairly with passengers.
- Setting a fair mileage reimbursement rate or charging clients for travel as a self-employed worker or contractor.
- Comparing two cars by their real driving cost per mile rather than just the sticker price or headline MPG.
- Deciding whether driving or another option (train, flight, rideshare) is cheaper for a given journey.
- Tracking how a change in fuel price or a switch to a more efficient car changes your annual running cost.
- Estimating the fuel cost of a delivery run or gig-economy shift to check it is actually worth taking.
How to use the Cost Per Mile Calculator
- Choose your unit system: US (gallon, MPG) or metric (litre, L/100km).
- Enter the fuel price you pay per gallon or per litre.
- Enter your fuel economy: MPG in US mode, or L/100km in metric mode.
- Optionally add a maintenance cost per mile and a trip distance.
- Read off the fuel cost per mile, total cost per mile, and the trip cost.
Formula & method
Worked examples
A car doing 30 MPG, fuel at $3.50 per gallon, with no maintenance figure, on a 100 mile trip.
- Fuel cost per mile = 3.50 / 30 = 0.11667
- Total cost per mile = 0.11667 + 0 = 0.11667
- Trip cost = 0.11667 x 100 = 11.67
Result: Fuel cost about $0.117 per mile, trip cost about $11.67
A car using 8 L/100km, fuel at 1.60 per litre, plus 0.05 per mile maintenance, on a 160 km trip.
- Cost per km = 1.60 x 8 / 100 = 0.128
- Fuel cost per mile = 0.128 / 0.621371 = 0.20600
- Total cost per mile = 0.20600 + 0.05 = 0.25600
- Trip distance in miles = 160 x 0.621371 = 99.42
- Trip cost = 0.25600 x 99.42 = 25.45
Result: Fuel cost about $0.206 per mile, total about $0.256 per mile, trip cost about $25.45
A pickup doing 18 MPG, fuel at $4.20 per gallon, plus 0.12 per mile maintenance, on a 250 mile trip.
- Fuel cost per mile = 4.20 / 18 = 0.23333
- Total cost per mile = 0.23333 + 0.12 = 0.35333
- Trip cost = 0.35333 x 250 = 88.33
Result: Fuel cost about $0.233 per mile, total about $0.353 per mile, trip cost about $88.33
Fuel cost per mile by MPG at different US fuel prices (price per gallon / MPG)
| Fuel economy | $3.00/gal | $4.00/gal | $5.00/gal |
|---|---|---|---|
| 15 MPG | $0.200 | $0.267 | $0.333 |
| 20 MPG | $0.150 | $0.200 | $0.250 |
| 30 MPG | $0.100 | $0.133 | $0.167 |
| 40 MPG | $0.075 | $0.100 | $0.125 |
| 50 MPG | $0.060 | $0.080 | $0.100 |
Quick conversions between US and metric driving figures
| Quantity | Relationship |
|---|---|
| 1 mile | 1.60934 km |
| 1 km | 0.621371 miles |
| 1 US gallon | 3.78541 litres |
| MPG to L/100km | 235.215 / MPG |
| L/100km to MPG | 235.215 / (L/100km) |
Annual fuel cost at 12,000 miles per year by cost per mile
| Fuel cost per mile | Cost per 12,000 miles |
|---|---|
| $0.08 | $960 |
| $0.12 | $1,440 |
| $0.16 | $1,920 |
| $0.20 | $2,400 |
| $0.30 | $3,600 |
Common mistakes to avoid
- Mixing up MPG and L/100km direction. Higher MPG means a more efficient car, but with L/100km lower is better. Entering an L/100km value into an MPG field (or the reverse) gives a wildly wrong cost per mile, so pick the right unit mode first.
- Treating fuel cost as the whole cost per mile. Fuel is only part of the picture. Tyres, servicing, insurance, depreciation and finance all add up. The fuel-only figure understates the true driving cost per mile, which is why a maintenance field is included.
- Using the official MPG instead of your real MPG. Manufacturer or label MPG is measured in ideal conditions. Real-world economy in city traffic, cold weather or with a loaded car is often lower, so the actual cost per mile is usually higher than the brochure suggests.
- Forgetting prices and economy change. Fuel prices move week to week and economy varies with how and where you drive. A cost per mile is a snapshot, so recheck it with current numbers before relying on it for budgeting or billing.
- Confusing a mileage reimbursement rate with true cost. A government mileage rate is a flat allowance meant to cover fuel, wear and some ownership costs on average. Your own gas cost per mile from this calculator is only the fuel (plus any maintenance you add), so do not treat the two as the same number.
- Rounding the fuel price too early. Rounding $3.499 up to $3.50 or a litre price to the nearest ten cents before dividing shifts the cost per mile slightly. Enter the exact pump price and let the calculator round the final result instead.
Glossary
- Cost per mile
- The total cost to drive one mile, here fuel cost per mile plus any maintenance cost per mile.
- MPG
- Miles per gallon, a measure of fuel economy used in the US and UK where a higher number is more efficient.
- L/100km
- Litres of fuel used per 100 kilometres, the metric economy measure where a lower number is more efficient.
- Maintenance per mile
- An allowance added per mile for wear items like tyres, brakes, oil and servicing, separate from fuel.
- Fuel economy
- How far a vehicle travels on a given amount of fuel, expressed as MPG or L/100km.
- Trip cost
- The total cost of a single journey, found by multiplying total cost per mile by the trip distance in miles.
- Mileage rate
- A flat per-mile allowance, such as an IRS or employer rate, used to reimburse driving without tracking exact fuel costs.
- Cost per km
- The cost to drive one kilometre, the metric equivalent of cost per mile, equal to cost per mile times 0.621371.
Frequently asked questions
How do I calculate cost per mile?
Divide the price you pay per gallon by your miles per gallon. So $3.50 fuel at 30 MPG is 3.50 / 30, about $0.117 per mile. Add a maintenance cost per mile if you want a fuller total. This cost per mile calculator does all of it for you.
How do I work out cost per mile from L/100km?
First find cost per km: price per litre times L/100km divided by 100. Then divide by 0.621371 to convert to cost per mile. For example 1.60 per litre at 8 L/100km gives 0.128 per km, which is about $0.206 per mile.
What is a typical fuel cost per mile?
It depends on the car and fuel price, but many everyday petrol cars land between roughly $0.10 and $0.20 per mile in fuel alone. Efficient hybrids can be lower and large trucks much higher. Use your own price and MPG for an accurate figure.
Should I include maintenance in cost per mile?
If you want a realistic running cost, yes. Fleets and self-employed drivers add a per-mile allowance for tyres, servicing and other wear. Enter it in the maintenance field and the total cost per mile will include it on top of fuel.
Does this include insurance and depreciation?
No. Insurance, depreciation and finance are large costs but they are not really per-mile, so they are left out. The true cost of owning a car is higher than the fuel-plus-maintenance figure shown by this mileage cost calculator.
Can I use this for electric vehicles?
Not directly, because the inputs assume liquid fuel measured in gallons or litres. For an EV you would calculate cost per mile from electricity price per kWh and the car efficiency in miles per kWh instead.
How do I find my real MPG for the calculator?
Fill the tank, note the odometer, then at the next fill divide the miles driven by the gallons added. Doing this over a few tanks gives a real-world MPG that reflects your driving, which makes the cost per mile far more accurate than the label figure.
How do I calculate the fuel cost of a whole trip?
Work out your total cost per mile, then multiply by the trip distance in miles. For example $0.15 per mile over a 200 mile trip is 0.15 x 200 = $30. Enter a distance in the trip field and this trip fuel cost calculator shows it automatically.
Is cost per mile the same as the IRS mileage rate?
No. The IRS standard mileage rate is a flat allowance covering fuel plus wear and some ownership costs on average. Your gas cost per mile here is just fuel and any maintenance you add, so it is usually lower than the reimbursement rate.
Why is my cost per mile higher than I expected?
Usually because of low real-world MPG, a high pump price, or a heavy or short-trip driving pattern. City traffic, cold starts and a loaded vehicle all cut economy, which raises the car cost per mile above the brochure estimate.
Sources
- Gas Mileage Tips and Fuel Economy , U.S. Department of Energy, fueleconomy.gov (2025)
- Standard Mileage Rates , U.S. Internal Revenue Service (2025)