⛽ Fuel Cost Calculator — What Will That Drive Cost?
← Life & LivingA quick trip, a long road trip, or the same commute every week — enter the distance, what your car uses, and the price at the pump. See the fuel bill, the cost per kilometre or mile, and what everyone pays if you're sharing the ride.
Here's the fuel bill
Estimate, based on your inputs — not a current fuel-price quotation or a promise about your car.
Your drive, in fuel and dollars
One seat or a full car?
Same drive, more seats filled — the fuel bill gets a little friendlier per person.
What if the pump price changes?
A more efficient drive can change the bill
The numbers behind the trip
| Distance entered | – |
|---|---|
| Distance charged | – |
| Fuel consumption | – |
| Fuel price | – |
| Estimated fuel used | – |
| Estimated fuel cost | – |
| Cost per distance | – |
| People sharing | – |
| Each person's fuel share | – |
This is a fuel-only estimate. Real fuel use can change with traffic, hills, weather, cargo and driving style. Enter a real-world consumption figure when you have one.
Every drive has a price tag. This one has a number.
A trip can feel cheap when the only price you see is the coffee you buy along the way. Then you fill up on the way home, and the numbers look a little different.
Fuel costs are easy to underestimate because distance, your car's fuel use and the price at the pump are three separate things. This calculator puts them together. You can see what the whole drive costs, what it works out to per kilometre or mile, and how little — or how much — each person owes when you share the ride.
It's just as handy for the everyday stuff. A short commute doesn't look like much until you multiply it by five days a week. A small change in fuel efficiency hardly shows up on one trip, but can look very different over a year.
You don't need to know the perfect answer before you start. Put in a reasonable estimate, explore the scenarios, then update it with your actual fuel consumption or current pump price when you have them.
Fuel maths has a few plot twists
⛽ The cheaper petrol station can actually cost more
Save 10 cents a litre on a 40-litre fill and you've saved $4. Nice. But if reaching that station adds 30 km to your drive, a car using 7.5 L/100 km burns another 2.25 litres. At $1.80 a litre, that's about $4.05 in extra fuel. The bargain is five cents worse before you even count your time.
📉 Half a litre sounds tiny. Ten thousand kilometres disagree
Improve fuel consumption by just 0.5 L/100 km and, over 10,000 km, that's 50 litres you didn't use. At an illustrative $1.80 a litre, that's $90 staying in your pocket. Little improvements get a lot louder over longer distances.
🚗 Four passengers can make a big drive feel like a small bill
A 350 km drive using 7.2 L/100 km at $1.90 a litre costs $47.88 in fuel. One person pays the lot. Four people sharing equally pay $11.97 each. Same road, same car, very different wallets.
🇬🇧 The number on a UK MPG sticker isn't the same as a US MPG sticker
A UK Imperial gallon holds about 20% more fuel than a US gallon. So 40 miles per Imperial gallon is only about 33.3 miles per US gallon. Two cars can show different MPG numbers even when their real fuel use is identical — just because their gallons aren't.
🔁 Your tiny commute has 240 chances to become a bigger number
Drive to work and back five days a week for 48 weeks, and that's 240 round trips. If work is 18 km away, you've driven 8,640 km before the weekend adventures even start. At 7.2 L/100 km and $1.90 a litre, that's about $1,181.95 in fuel — just for getting there and back.
All prices and driving figures above are illustrative examples, not current local fuel rates.
How does the fuel cost calculator work?
The basic idea is simple: work out how much fuel the journey needs, then multiply it by what that fuel costs. Distance, fuel consumption and the price at the pump do the heavy lifting.
If your car shows litres per 100 km
Fuel used (L) = Total distance (km) × Consumption (L/100 km) ÷ 100
Fuel cost = Fuel used (L) × Price per litre
Say you drive 350 km in a car using 7.2 L/100 km and petrol costs $1.90 per litre. The drive uses 350 × 7.2 ÷ 100 = 25.2 litres. At $1.90 per litre, the fuel costs $47.88.
If your car shows US miles per gallon
US gallons used = Total distance (miles) ÷ US miles per gallon
Fuel cost = US gallons used × Price per US gallon
A 200-mile drive at 25 US MPG uses 8 US gallons. At $3.75 per US gallon, the fuel cost is $30.00. The same method works for UK MPG only when you pair it with the Imperial gallon, not a US gallon.
What if my car shows km per litre or UK MPG?
The calculator converts every valid fuel-efficiency and price unit to the same internal measurement: kilometres, litres per 100 kilometres and money per litre. That makes the figures comparable without mixing different gallon sizes.
L/100 km from km/L = 100 ÷ (km/L)
L/100 km from US MPG ≈ 235.2145833 ÷ (US MPG)
L/100 km from UK MPG ≈ 282.4809363 ÷ (UK MPG)
When you switch units, the calculator converts the value you entered; it does not pretend 7.2 L/100 km means 7.2 miles per gallon.
One-way vs return trip
Total trip distance = One-way distance × 2, if return trip is selected
The distance box is always one-way. If you tick return trip, the calculator counts the journey home too. It won't assume you have a different route on the way back.
Splitting and recurring trips
Exact share = rounded trip-total cents divided among the selected people, with leftover cents distributed individually
Annual fuel cost = unrounded trip cost × trips each week × driving weeks each year
Average month = annual fuel cost ÷ 12
For a group, each share is worked out in cents so the displayed payments add up to the full fuel bill. For commutes, the calculator multiplies your chosen trip by how often it happens; it doesn't guess your days off or public holidays.
Assumptions worth knowing
- The result assumes the selected consumption figure holds for the whole drive and the pump price is the same for all fuel used.
- Your car's published efficiency rating may differ from real-world usage due to speed, congestion, terrain, weather, load, tyres and driving technique.
- Only fuel is included. Tolls, parking, insurance, servicing, wear and tear, vehicle depreciation and time are excluded.
- Evenly shared fuel is a calculation, not a judgement about who should pay.
- Return distance is modelled as double the entered one-way distance; actual out-and-back routes may differ.
- Weekly and annual commuting estimates use user-specified frequencies and an annualised projection, not live calendar days.
- Currency selection formats values; it is not a currency converter.
- Fuel prices are editable examples; the calculator does not show live station data.
Sources for unit accuracy and helpful context
- NIST unit conversion reference (US and Imperial gallons)
- NIST SI conversion reference, including miles and US MPG
- US Department of Energy — driving behaviour and fuel economy
- FuelEconomy.gov — the official US vehicle fuel-economy resource
NIST is the source for the unit conversions; the Department of Energy explains why real-world fuel use varies. Neither supplied the example prices on this page.
Fuel Cost Calculator FAQs
How do I calculate the fuel cost of a trip?
Multiply your journey's distance in kilometres by your car's litres per 100 km, then divide by 100 to get litres needed. Multiply those litres by your price per litre. This calculator does those steps for you and can also work with miles and MPG.
Should I enter the full journey or just the distance there?
Enter the one-way distance. Switch on Return trip if you're driving back along a journey of roughly the same length. The calculator doubles the distance automatically, so don't double the input as well.
What is the difference between L/100 km and MPG?
L/100 km tells you how many litres your car uses over 100 km, so lower is better. MPG tells you how far the car travels on a gallon, so higher is better. UK and US gallons are different sizes; choose the MPG unit that matches your car's figures.
How accurate is a fuel cost calculator?
The arithmetic is reliable, but the estimate is only as accurate as your inputs. Actual fuel use changes with driving conditions and how your car is loaded, while pump prices vary. Your own average consumption over several fill-ups is often more useful for budgeting than an optimistic advertised number.
Does it include tolls, parking and other car costs?
No. The headline is for fuel only. Parking, tolls, maintenance, insurance, loan repayments and the cost of buying or depreciating the vehicle sit outside it. Keep those separate if you're comparing the full cost of driving with another way of travelling.
How do I split petrol money with friends?
Enter how many people are sharing the fuel bill, including the driver if the driver is paying an equal share. The calculator divides the estimated fuel total between them and handles any leftover cents so the amounts add up exactly.
Can I use this for my commute?
Yes. Enter the one-way journey to work, tick Return trip if you're driving home, and open the recurring-trip option. Choose the number of commute days each week and the number of weeks you expect to drive each year to see a weekly, average monthly and annual estimate.
Does choosing USD or GBP automatically update fuel prices?
No. Changing currency changes the money label, not the exchange rate or the fuel price at a local station. Enter the pump price you actually pay in the chosen currency and specify whether it is per litre, US gallon or Imperial gallon.
How much fuel do I need for a 500 km road trip?
There's no universal answer — it depends on the car. At 7.2 L/100 km, 500 km needs 500 × 7.2 ÷ 100 = 36 litres. A car using 9 L/100 km would need 45 litres for the same drive. Put your own consumption figure into the calculator to get your number.
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