Fuel Cost Calculator
Use our fuel cost calculator to quickly estimate how much you’ll spend on petrol or diesel journey costs over a week, month, or year.
Unlike many online fuel calculators that require journey planning, postcode, and complex steps, this tool is designed to give you a helpful estimate in seconds using just three simple inputs: fuel price, annual mileage, and MPG (miles per gallon).
Whether you're budgeting your annual driving costs, comparing vehicles, or planning ahead, it’s a quick and practical way to understand your fuel spend.
Get a free valuation
How do I calculate my fuel costs?
Enter the following details to get started:
- Fuel price (per litre) – the current cost of petrol or diesel
- Annual mileage – how many miles you drive in a year
- MPG – your car’s fuel efficiency
You can use the manufacturer-reported MPG for a quick estimate, or your real-world reading for a more accurate result. If you’re unsure about this, read our guide on MPG or use our MPG calculator to get your own reading.
What our fuel cost calculator shows you
Based on your inputs, our tool automatically calculates your:
- Weekly fuel cost – useful for short-term budgeting
- Monthly fuel cost – helps you understand your regular running costs
- Annual fuel cost – shows your total fuel spend over a year
This makes it easier to:
- Budget your fuel costs at any level
- Compare different vehicles or MPG figures
- Understand how changes in mileage or fuel price affect your overall spend
- Estimate the fuel cost for a specific trip or journey
Weekly and monthly costs are based on your annual estimate.
Our tool can also be used as a journey fuel cost calculator. If you want to calculate fuel cost for a trip, simply enter the distance of your journey as your annual mileage.
The tool will treat this as a one-off journey and display the estimated cost in the annual fuel cost field, along with fuel usage in gallons and litres.
How our fuel cost calculator works
The calculator estimates how much fuel your car will use over a year, then multiplies it by the fuel price.
Inputs explained:
| Input | What it means | Example |
|---|---|---|
| Fuel price | Cost per litre | £1.55 |
| Annual mileage | Miles driven per year | 10,000 miles |
| MPG | Fuel efficiency | 45 MPG |
When you submit these figures, our tool:
- Calculates how many gallons of fuel your car will use.
- Converts that into litres (as fuel is sold in litres in the UK).
- Multiplies this by the price per litre.
This gives you a clear picture of how your fuel costs may look over time.
Fuel cost formula
Want to calculate your fuel costs manually? Here's how it works:
- Fuel used (gallons) = Annual mileage ÷ MPG
- Fuel used (litres) = Gallons × 4.546
- Total fuel cost = litres × price per litre
Why it's worth double-checking your results
Fuel cost calculators provide a reliable estimate, but your result is only as accurate as the inputs you use.
Sense checking helps you:
- Spot incorrect figures quickly
- Avoid underestimating fuel costs
- Make more confident decisions when budgeting or comparing cars
What to check
- Fuel price
For accurate and current local fuel prices, check local forecourt signage or use a Fuel Finder enabled fuel comparison app.
- MPG (fuel efficiency)
Real-world MPG is often lower than official figures, especially for short or urban journeys. Recording your own MPG can produce more accurate results.
- Annual mileage
Check your MOT history, recent mileage readings, and typical driving patterns to sense check your annual estimate.
What is my car's MPG?
Your MPG has a big impact on your fuel costs; even small differences can add up significantly over a year. If you're unsure of your MPG, here are a few ways to find it:
- Use the manufacturer's MPG figure: This is a quick starting point and useful for rough estimates, but it's often optimistic. Real-world MPG is usually lower due to traffic, driving style, and road conditions.
- Track fuel usage between fill-ups: This gives you a more accurate, real-world MPG figure:
- Fill your tank fully and reset your trip counter.
- Drive as normal.
- Refill the tank and note how many litres you've used.
- Record the miles driven from your trip counter.
- Convert litres to gallons (divide by 4.546), then calculate: MPG = miles driven ÷ gallons used.
- Use our MPG calculator: Enter your mileage and fuel usage to quickly estimate your car's real-world fuel efficiency without manual calculations.
Where do I find my fuel cost per litre?
To find your fuel cost per litre, look for the forecourt signage at your local petrol station. This should show accurate pricing for all available fuels.
Alternatively, fuel price comparison and navigation apps integrated with the government's Fuel Finder service, will show the latest available pricing data. This can be helpful for finding the cheapest fuel in your area.
As of April 2026, around 90% of petrol stations are signed up to the Fuel Finder scheme, which requires stations to report any pricing changes within 30 minutes. The government has stated that it requires the remainder to start sharing pricing data with Fuel Finder.
Example fuel cost calculations
To help you sense check your results, here are some examples based on typical UK fuel prices in April 2026:
- Petrol: £1.55 per litre
- Diesel: £1.85 per litre
Please note: Prices vary by location, so use your local fuel price for the most accurate estimate.
These examples also use average annual mileages for UK drivers, based on Department for Transport (DfT) data:
- Petrol cars: 6,100 miles per year
- Diesel cars: 8,300 miles per year
Source: DfT - NTS0901: Annual mileage of cars by ownership, fuel type and trip purpose: England, 2002 onwards
Example 1: Petrol car
- Annual mileage: 6,100 miles
- MPG: 45
- Fuel price per litre: £1.55
Calculation:
- 6,100 ÷ 45 = 135.6 gallons
- 135.6 × 4.546 = 616 litres
- 616 × £1.55 = £955
Estimated annual fuel cost: £955
Example 2: Diesel car
- Annual mileage: 8,300 miles
- MPG: 55
- Fuel price per litre: £1.85
Calculation:
- 8,300 ÷ 55 = 150.9 gallons
- 150.9 × 4.546 = 686 litres
- 686 × £1.85 = £1,269
Estimated annual fuel cost: £1,269
Petrol vs diesel cost calculator
Choosing between petrol and diesel isn't just about the price at the pump. Overall running costs are what really count.
You can compare the real costs of each fuel type using our petrol vs diesel fuel cost calculator. Simply enter your annual mileage, MPG, and fuel price per litre to see how much each option could cost over time.
Fuel costs mainly depend on:
- Price per litre
- Fuel efficiency (MPG)
In general:
- Petrol is usually cheaper per litre but less fuel-efficient.
- Diesel costs more per litre but often delivers better MPG.
The most cost-effective option depends on how and where you drive. For example, higher-mileage drivers may benefit from diesel's efficiency, while lower-mileage or city drivers may find petrol more affordable overall.
Our tool works as both a petrol and diesel fuel cost calculator, allowing you to quickly compare both fuel types side by side. You can also use it as a diesel fuel cost calculator to focus specifically on diesel running costs.
By adjusting your inputs, you can see which option could cost you less over a week, month, or year, helping you make a more informed decision.
Tips for a more accurate fuel price estimate
Fuel prices can vary significantly across the UK depending on the location, retailer, and even time of day.
To improve accuracy:
- Use current local prices: Check the price you typically pay at your nearest petrol station, rather than relying on national averages
- Avoid motorway prices (unless you regularly refuel there): Motorway service stations typically charge a premium, often around 15p to 20p more per litre than supermarket fuel prices. For a 55-litre car, that could mean paying an extra £8-£11 per tank!
- Compare nearby forecourts: Prices can vary between stations in the same area, so it's worth checking a few options before choosing a price to use.
Quick fuel saving tips
- Drive smoothly and avoid harsh acceleration.
- Utilise fuel-saving features such as start/stop and cruise control, if available.
- Try to minimise the use of features that consume fuel, such as heated seats.
- Keep your tyres properly inflated, check the pressure regularly, and replace them before the tread falls below 3mm.
- Stay on top of your vehicle's servicing schedule.
- Remove unnecessary weight before travel.
- Use alternative transport for shorter journeys where practical.
- Consider carpooling with a colleague living nearby to save on commuting costs.
- Always compare fuel prices before filling up.
Fuel costs mounting up? Sell your car in under an hour with webuyanycar
Older cars can become less efficient over time due to wear and tear, while newer models often deliver better fuel economy thanks to advances in technology.
If your fuel costs are higher than expected, it could be time to make a change.
You can sell your car in under an hour at any of webuyanycar's 550+ UK branches, with an average drive time of just 11 minutes!
Enter your reg and mileage into our free car valuation tool to find out how much your car could be worth.
Fuel Cost FAQs
It depends on how you drive. Diesel cars are usually more fuel-efficient (higher MPG), which can make them cheaper for longer journeys or higher annual mileage. However, diesel typically costs more per litre than petrol, so petrol may be more cost-effective for lower mileage or mainly urban driving.
DfT data also shows diesel cars tend to cover more miles per year than petrol cars, which is one reason diesel models can still suit higher-mileage drivers.
A fuel cost calculator is designed to give a useful guideline, rather than an exact figure. Your result will vary depending on how accurate your inputs are and how fuel prices change over time.
The main fuel cost factors are your annual mileage, your car's MPG (fuel efficiency), the price you pay per litre.
You can estimate your annual mileage using a simple weekly average:
- At the beginning of a typical week, reset your trip counter before driving.
- Record the mileage travelled at the end of the week.
- Multiply this figure by 52 to estimate your annual mileage.
For a more accurate estimate, repeat this over a few weeks and take an average.
Alternatively, you can refer to the mileage recorded in your vehicle's MOT or service history to see how your mileage has changed year to year.
Bear in mind that your driving patterns may vary, and figures from years affected by national Coronavirus restrictions may not reflect your usual mileage.
You only need three figures: your annual mileage, MPG, and fuel price per litre.
Our fuel cost calculator uses these to estimate your yearly fuel spend, then breaks it down into monthly and weekly fuel costs automatically.
If you're calculating your annual cost manually, use this formula:
Fuel cost = (Annual mileage ÷ MPG) × 4.546 × fuel price per litre
Then:
- Monthly fuel cost = annual ÷ 12
- Weekly fuel cost = annual ÷ 52
This depends on your car's fuel tank size and the price per litre. To estimate the cost of a full tank, use this formula:
Fill-up cost = tank size (litres) × fuel price per litre
This assumes you're filling the tank from empty. In practice, you'll usually only pay for the fuel needed to top up.
For context, the average fuel tank capacity of a car is around 53 litres, although this varies by vehicle size.
More broadly, most cars fall within a range of roughly 38 to 76 litres, with smaller cars at the lower end and larger vehicles at the higher end.
The easiest way is to use our fuel cost calculator as a journey fuel cost calculator. To calculate fuel cost for a trip, simply enter your journey distance as your annual mileage, and the tool will estimate the total cost along with fuel usage in litres and gallons.
To manually estimate a journey cost, you'll need:
- Trip distance (in miles)
- Your car's MPG (miles per gallon)
- Fuel price per litre
Use the same method as you would to work out annual fuel cost, replacing annual mileage with your trip distance:
Fuel cost = (Distance in miles ÷ MPG) × 4.546 × fuel price per litre
This works by calculating how much fuel your car will use in gallons, converting it to litres (as fuel is sold in litres in the UK), and then multiplying by the price per litre.
This gives you a quick estimate of how much fuel your trip will use and what it will cost.
How do I calculate my fuel costs?
Enter the following details to get started:
- Fuel price (per litre) – the current cost of petrol or diesel
- Annual mileage – how many miles you drive in a year
- MPG – your car’s fuel efficiency
You can use the manufacturer-reported MPG for a quick estimate, or your real-world reading for a more accurate result. If you’re unsure about this, read our guide on MPG or use our MPG calculator to get your own reading.
What our fuel cost calculator shows you
Based on your inputs, our tool automatically calculates your:
- Weekly fuel cost – useful for short-term budgeting
- Monthly fuel cost – helps you understand your regular running costs
- Annual fuel cost – shows your total fuel spend over a year
This makes it easier to:
- Budget your fuel costs at any level
- Compare different vehicles or MPG figures
- Understand how changes in mileage or fuel price affect your overall spend
- Estimate the fuel cost for a specific trip or journey
Weekly and monthly costs are based on your annual estimate.
Our tool can also be used as a journey fuel cost calculator. If you want to calculate fuel cost for a trip, simply enter the distance of your journey as your annual mileage.
The tool will treat this as a one-off journey and display the estimated cost in the annual fuel cost field, along with fuel usage in gallons and litres.
How our fuel cost calculator works
The calculator estimates how much fuel your car will use over a year, then multiplies it by the fuel price.
Inputs explained:
| Input | What it means | Example |
|---|---|---|
| Fuel price | Cost per litre | £1.55 |
| Annual mileage | Miles driven per year | 10,000 miles |
| MPG | Fuel efficiency | 45 MPG |
When you submit these figures, our tool:
- Calculates how many gallons of fuel your car will use.
- Converts that into litres (as fuel is sold in litres in the UK).
- Multiplies this by the price per litre.
This gives you a clear picture of how your fuel costs may look over time.
Fuel cost formula
Want to calculate your fuel costs manually? Here's how it works:
- Fuel used (gallons) = Annual mileage ÷ MPG
- Fuel used (litres) = Gallons × 4.546
- Total fuel cost = litres × price per litre
Why it's worth double-checking your results
Fuel cost calculators provide a reliable estimate, but your result is only as accurate as the inputs you use.
Sense checking helps you:
- Spot incorrect figures quickly
- Avoid underestimating fuel costs
- Make more confident decisions when budgeting or comparing cars
What to check
- Fuel price
For accurate and current local fuel prices, check local forecourt signage or use a Fuel Finder enabled fuel comparison app.
- MPG (fuel efficiency)
Real-world MPG is often lower than official figures, especially for short or urban journeys. Recording your own MPG can produce more accurate results.
- Annual mileage
Check your MOT history, recent mileage readings, and typical driving patterns to sense check your annual estimate.
What is my car's MPG?
Your MPG has a big impact on your fuel costs; even small differences can add up significantly over a year. If you're unsure of your MPG, here are a few ways to find it:
- Use the manufacturer's MPG figure: This is a quick starting point and useful for rough estimates, but it's often optimistic. Real-world MPG is usually lower due to traffic, driving style, and road conditions.
- Track fuel usage between fill-ups: This gives you a more accurate, real-world MPG figure:
- Fill your tank fully and reset your trip counter.
- Drive as normal.
- Refill the tank and note how many litres you've used.
- Record the miles driven from your trip counter.
- Convert litres to gallons (divide by 4.546), then calculate: MPG = miles driven ÷ gallons used.
- Use our MPG calculator: Enter your mileage and fuel usage to quickly estimate your car's real-world fuel efficiency without manual calculations.
Where do I find my fuel cost per litre?
To find your fuel cost per litre, look for the forecourt signage at your local petrol station. This should show accurate pricing for all available fuels.
Alternatively, fuel price comparison and navigation apps integrated with the government's Fuel Finder service, will show the latest available pricing data. This can be helpful for finding the cheapest fuel in your area.
As of April 2026, around 90% of petrol stations are signed up to the Fuel Finder scheme, which requires stations to report any pricing changes within 30 minutes. The government has stated that it requires the remainder to start sharing pricing data with Fuel Finder.
Example fuel cost calculations
To help you sense check your results, here are some examples based on typical UK fuel prices in April 2026:
- Petrol: £1.55 per litre
- Diesel: £1.85 per litre
Please note: Prices vary by location, so use your local fuel price for the most accurate estimate.
These examples also use average annual mileages for UK drivers, based on Department for Transport (DfT) data:
- Petrol cars: 6,100 miles per year
- Diesel cars: 8,300 miles per year
Source: DfT - NTS0901: Annual mileage of cars by ownership, fuel type and trip purpose: England, 2002 onwards
Example 1: Petrol car
- Annual mileage: 6,100 miles
- MPG: 45
- Fuel price per litre: £1.55
Calculation:
- 6,100 ÷ 45 = 135.6 gallons
- 135.6 × 4.546 = 616 litres
- 616 × £1.55 = £955
Estimated annual fuel cost: £955
Example 2: Diesel car
- Annual mileage: 8,300 miles
- MPG: 55
- Fuel price per litre: £1.85
Calculation:
- 8,300 ÷ 55 = 150.9 gallons
- 150.9 × 4.546 = 686 litres
- 686 × £1.85 = £1,269
Estimated annual fuel cost: £1,269
Petrol vs diesel cost calculator
Choosing between petrol and diesel isn't just about the price at the pump. Overall running costs are what really count.
You can compare the real costs of each fuel type using our petrol vs diesel fuel cost calculator. Simply enter your annual mileage, MPG, and fuel price per litre to see how much each option could cost over time.
Fuel costs mainly depend on:
- Price per litre
- Fuel efficiency (MPG)
In general:
- Petrol is usually cheaper per litre but less fuel-efficient.
- Diesel costs more per litre but often delivers better MPG.
The most cost-effective option depends on how and where you drive. For example, higher-mileage drivers may benefit from diesel's efficiency, while lower-mileage or city drivers may find petrol more affordable overall.
Our tool works as both a petrol and diesel fuel cost calculator, allowing you to quickly compare both fuel types side by side. You can also use it as a diesel fuel cost calculator to focus specifically on diesel running costs.
By adjusting your inputs, you can see which option could cost you less over a week, month, or year, helping you make a more informed decision.
Tips for a more accurate fuel price estimate
Fuel prices can vary significantly across the UK depending on the location, retailer, and even time of day.
To improve accuracy:
- Use current local prices: Check the price you typically pay at your nearest petrol station, rather than relying on national averages
- Avoid motorway prices (unless you regularly refuel there): Motorway service stations typically charge a premium, often around 15p to 20p more per litre than supermarket fuel prices. For a 55-litre car, that could mean paying an extra £8-£11 per tank!
- Compare nearby forecourts: Prices can vary between stations in the same area, so it's worth checking a few options before choosing a price to use.
Quick fuel saving tips
- Drive smoothly and avoid harsh acceleration.
- Utilise fuel-saving features such as start/stop and cruise control, if available.
- Try to minimise the use of features that consume fuel, such as heated seats.
- Keep your tyres properly inflated, check the pressure regularly, and replace them before the tread falls below 3mm.
- Stay on top of your vehicle's servicing schedule.
- Remove unnecessary weight before travel.
- Use alternative transport for shorter journeys where practical.
- Consider carpooling with a colleague living nearby to save on commuting costs.
- Always compare fuel prices before filling up.
Fuel costs mounting up? Sell your car in under an hour with webuyanycar
Older cars can become less efficient over time due to wear and tear, while newer models often deliver better fuel economy thanks to advances in technology.
If your fuel costs are higher than expected, it could be time to make a change.
You can sell your car in under an hour at any of webuyanycar's 550+ UK branches, with an average drive time of just 11 minutes!
Enter your reg and mileage into our free car valuation tool to find out how much your car could be worth.
Fuel Cost FAQs
It depends on how you drive. Diesel cars are usually more fuel-efficient (higher MPG), which can make them cheaper for longer journeys or higher annual mileage. However, diesel typically costs more per litre than petrol, so petrol may be more cost-effective for lower mileage or mainly urban driving.
DfT data also shows diesel cars tend to cover more miles per year than petrol cars, which is one reason diesel models can still suit higher-mileage drivers.
A fuel cost calculator is designed to give a useful guideline, rather than an exact figure. Your result will vary depending on how accurate your inputs are and how fuel prices change over time.
The main fuel cost factors are your annual mileage, your car's MPG (fuel efficiency), the price you pay per litre.
You can estimate your annual mileage using a simple weekly average:
- At the beginning of a typical week, reset your trip counter before driving.
- Record the mileage travelled at the end of the week.
- Multiply this figure by 52 to estimate your annual mileage.
For a more accurate estimate, repeat this over a few weeks and take an average.
Alternatively, you can refer to the mileage recorded in your vehicle's MOT or service history to see how your mileage has changed year to year.
Bear in mind that your driving patterns may vary, and figures from years affected by national Coronavirus restrictions may not reflect your usual mileage.
You only need three figures: your annual mileage, MPG, and fuel price per litre.
Our fuel cost calculator uses these to estimate your yearly fuel spend, then breaks it down into monthly and weekly fuel costs automatically.
If you're calculating your annual cost manually, use this formula:
Fuel cost = (Annual mileage ÷ MPG) × 4.546 × fuel price per litre
Then:
- Monthly fuel cost = annual ÷ 12
- Weekly fuel cost = annual ÷ 52
This depends on your car's fuel tank size and the price per litre. To estimate the cost of a full tank, use this formula:
Fill-up cost = tank size (litres) × fuel price per litre
This assumes you're filling the tank from empty. In practice, you'll usually only pay for the fuel needed to top up.
For context, the average fuel tank capacity of a car is around 53 litres, although this varies by vehicle size.
More broadly, most cars fall within a range of roughly 38 to 76 litres, with smaller cars at the lower end and larger vehicles at the higher end.
The easiest way is to use our fuel cost calculator as a journey fuel cost calculator. To calculate fuel cost for a trip, simply enter your journey distance as your annual mileage, and the tool will estimate the total cost along with fuel usage in litres and gallons.
To manually estimate a journey cost, you'll need:
Trip distance (in miles)
Your car's MPG (miles per gallon)Fuel price per litreUse the same method as you would to work out annual fuel cost, replacing annual mileage with your trip distance:
Fuel cost = (Distance in miles ÷ MPG) × 4.546 × fuel price per litre
This works by calculating how much fuel your car will use in gallons, converting it to litres (as fuel is sold in litres in the UK), and then multiplying by the price per litre.
This gives you a quick estimate of how much fuel your trip will use and what it will cost.
