Fuel Cost Calculator

Three free calculators for Irish drivers: work out how much a journey costs, how much a fill-up costs, and how much you could save by switching to a cheaper station.

1. Journey Cost

Enter your journey distance, fuel consumption, and the price per litre to find out how much the trip will cost in fuel.

L/100km MPG
Enter values above to see the journey cost.

How it works: Journey cost = (distance / 100) x consumption (L/100km) x price per litre. If you enter MPG, the calculator converts it to L/100km using 282.48 / MPG before calculating. Typical Irish mixed-driving consumption is 5.5 to 8 L/100km depending on the car.

2. Fill-Up Cost

How much will it cost to put a certain number of litres in your tank at the current pump price?

Enter values above to see the fill-up cost.

How it works: Fill-up cost = litres x price per litre. Most Irish petrol and diesel cars have tanks between 40 and 70 litres. Home heating oil and agricultural diesel tanks are much larger. Enter any volume and the current community-reported price from FuelWatch to get an instant total.

3. Price Comparison Saving

Compare two prices per litre and see exactly how much you would save per fill-up and over a full year.

Annual saving assumes the same number of fills every month.

Enter two prices to see your saving.

How it works: Saving per fill = (Price A - Price B) x fill litres. Annual saving = saving per fill x fills per month x 12. Even a small price difference adds up: 5 cent per litre on a 50-litre fill is EUR 2.50 per visit, EUR 60 over a year at two fills a month. Use FuelWatch to find community-reported prices at stations near you before you fill up.

Find the Cheapest Price Near You

Plug in live pump prices from FuelWatch to get exact results. The FuelWatch app shows community-reported petrol and diesel prices at stations across all 32 counties of Ireland, so you can always find the cheapest forecourt before you fill up.

Open the Web App Download on the App Store

Frequently Asked Questions

Divide your journey distance (km) by 100, multiply by your car's fuel consumption in L/100km, then multiply by the current price per litre in EUR. For example: 200 km, 6.5 L/100km, EUR 1.85/litre gives (200 / 100) x 6.5 x 1.85 = EUR 24.05. The Journey Cost calculator above does this instantly.
Most modern petrol cars use between 5.5 and 7.5 litres per 100 km under mixed city and motorway driving. Diesel cars tend to be more efficient, typically 4.5 to 6.5 litres per 100 km. SUVs and older vehicles can consume 8 to 12 litres per 100 km or more. Electric vehicles use 15 to 25 kWh per 100 km.
It depends on your tank size and the current price per litre. A typical 50-litre petrol tank at EUR 1.85/litre costs EUR 92.50 to fill. Larger tanks (60 to 70 litres) cost EUR 111 to EUR 129.50 at the same price. Use the Fill-Up Cost calculator above with today's community-reported price from FuelWatch to get an accurate figure.
Even small price differences compound quickly. A 5 cent per litre difference on a 50-litre fill saves EUR 2.50 per visit. Filling up twice a month saves EUR 60 per year. At 10 cent per litre the annual saving doubles to EUR 120. The Price Comparison calculator above shows your personalised saving based on the actual prices and your fill-up habits.
To convert UK MPG (imperial gallons) to L/100km, divide 282.48 by the MPG figure. For example, 45 MPG = 282.48 / 45 = 6.28 L/100km. The Journey Cost calculator above has an MPG toggle so you can enter MPG directly without doing the conversion yourself.
FuelWatch Ireland shows community-reported petrol and diesel prices at stations across all 32 counties. Open the free web app at app.fuelwatch.ie or download the iOS app to see the map and find the cheapest forecourt near your location before you fill up.