By the Numbers
By the Numbers: Petrol at 152.29p — Run Your Summer Trip Cost
Turn the latest official UK petrol and diesel prices into 100, 300, and 600-mile fuel-cost scenarios.
The UK government's latest weekly figures put average unleaded petrol at 152.29p per litre and diesel at 167.08p per litre. Turning those pump prices into a trip total requires two more numbers: distance and fuel economy.
This article uses the Fuel Cost Calculator to model a summer journey in kilometres and litres per 100km.
The story number
The Department for Energy Security and Net Zero's weekly road fuel prices for the week beginning 20 July 2026 report:
| Fuel | Average UK pump price | Previous week |
|---|---|---|
| Unleaded petrol | 152.29p/litre | 150.53p/litre |
| Diesel | 167.08p/litre | 164.52p/litre |
That is a weekly rise of 1.76p per litre for petrol and 2.56p for diesel.
The number to run
The calculator uses:
`litres needed = distance in km × litres per 100km ÷ 100`
`trip cost = litres needed × price per litre`
For readers starting with miles:
`kilometres = miles × 1.609344`
The assumptions
Our main scenario uses:
- 300 miles, converted to 482.8km
- fuel economy of 7.0 litres per 100km
- petrol at £1.5229 per litre
- no idling, detours or difference between outbound and return efficiency
Run the numbers
Fuel needed:
`482.8 × 7 ÷ 100 = 33.80 litres`
Petrol cost:
`33.80 × £1.5229 = £51.47`
At the diesel price, the same distance and 7.0L/100km assumption would cost about £56.46.
| Distance | Fuel at 7.0L/100km | Petrol cost at £1.5229/L |
|---|---|---|
| 100 miles / 160.9km | 11.27 litres | £17.16 |
| 300 miles / 482.8km | 33.80 litres | £51.47 |
| 600 miles / 965.6km | 67.59 litres | £102.95 |
What did the weekly price change add?
For the 300-mile example, applying the prior week's petrol price of £1.5053 per litre gives about £50.87.
At the latest price, the estimate is £51.47. The weekly pump-price movement therefore adds about 60p to this particular trip.
That result is useful context: the headline price rise is real, but distance and fuel economy can have a larger effect on the total.
For example, the same 300 miles at the latest petrol price would cost roughly:
| Fuel economy | Estimated cost |
|---|---|
| 5.5L/100km | £40.45 |
| 7.0L/100km | £51.47 |
| 9.0L/100km | £66.18 |
What the result means
Pump price is only one of the inputs. A driver cannot infer a trip cost from “152.29p per litre” without also knowing how far the vehicle will travel and how much fuel it uses over that distance.
The calculation also keeps unlike measures separate:
- pence per litre is a fuel price
- litres per 100km is an efficiency or consumption rate
- pounds is the resulting trip estimate
Try your own numbers
Enter your planned distance, realistic fuel economy and a local pump price in the Fuel Cost Calculator.
For a broader ownership estimate that includes insurance, maintenance and depreciation, use the Cost Per Mile Calculator. The Travel Time Calculator can model the same route's duration.
Caveats and source notes
- Government figures are weekly UK averages, not a quote for a particular filling station.
- Real-world fuel economy varies with the vehicle, route, speed, traffic, load, weather and driving style.
- Petrol and diesel vehicles often have different efficiency, so the equal-efficiency comparison above isolates price rather than representing two specific cars.
- This is a planning estimate, not a recommendation about a route, fuel or vehicle.
Source: Department for Energy Security and Net Zero, Weekly road fuel prices, updated 21 July 2026.
