Work out what a journey or a full tank costs at this week's UK average pump prices, and how much of every litre goes in tax.
Prices for week commencing Monday 28 September 2026, source: DESNZ, published on GOV.UK 29 September 2026. Fuel duty checked against HMRC on 1 October 2026.
| Fuel | Pump price | Fuel duty | VAT | Everything else | Tax share |
|---|---|---|---|---|---|
| Petrol | 173.46p | 52.95p | 28.91p | 91.60p | 47% |
| Diesel | 197.58p | 52.95p | 32.93p | 111.70p | 43% |
| Week commencing | Petrol | Diesel |
|---|---|---|
| 28 September 2026 | 173.46p | 197.58p |
| 21 September 2026 | 172.01p | 195.53p |
| 14 September 2026 | 168.14p | 190.72p |
| 7 September 2026 | 164.40p | 186.36p |
| 31 August 2026 | 161.61p | 183.49p |
| 24 August 2026 | 161.63p | 182.82p |
| 17 August 2026 | 161.80p | 182.45p |
| 10 August 2026 | 162.15p | 181.97p |
A year earlier, in the week commencing 29 September 2025, petrol averaged 134.36p and diesel 142.24p a litre.
The average prices on this page come from the Department for Energy Security and Net Zero, which publishes UK average pump prices for unleaded petrol and diesel every week. The prices are collected on a Monday and are normally published on GOV.UK the next day. Our system fetches the new file every Tuesday morning, so the week shown at the top of the page is always the latest one that has been released.
The journey cost starts with the miles per gallon figure you enter. A UK gallon is 4.54609 litres, as set out in the Weights and Measures Act 1985, so the calculator divides your distance by your MPG, multiplies by 4.54609 to get litres, then multiplies by the price per litre. The price box starts at the UK average, and you can type in the price on your local forecourt instead.
The tax figures use two rates from GOV.UK. Fuel duty on unleaded petrol and diesel is 52.95p a litre, the rate HMRC lists for both fuels. VAT is charged at 20% on the whole pump price, including the duty, so VAT is 20/120 of what you pay at the pump. On a litre of petrol at 173.46p that is 52.95p of duty and 28.91p of VAT, which leaves 91.60p to pay for the fuel itself, getting it to the forecourt and the retailer's margin.
There are limits worth knowing. The DESNZ figure is a national average, so prices at a single forecourt can be well above or below it. Your real MPG changes with speed, traffic, load and the weather, so a trip can cost more or less than the calculator suggests. The calculator does not cover premium fuels, AdBlue or electric charging.
If the government changes fuel duty, our weekly update checks the HMRC rate page and the DESNZ file and records both, so the breakdown follows the change. Every figure on this page can be checked against the sources listed below.
At this week's UK average of 173.46p a litre, fuel duty is 52.95p and VAT is 28.91p, so tax makes up 47% of the price. For diesel at 197.58p the share is 43%.
Divide the miles by your car's miles per gallon, multiply by 4.54609 to turn gallons into litres, then multiply by the price per litre. A 100 mile trip in a car that does 45 mpg uses about 10.1 litres, which costs about £17.52 at this week's average petrol price.
The Department for Energy Security and Net Zero publishes new UK averages every week, usually on a Tuesday, for prices collected on the Monday. This page updates itself after each release, and the week shown at the top tells you which figures you are looking at.