What Is the Cheapest Day to Buy Petrol in the UK? ⛽
If you've ever wondered whether filling up on a Monday saves money compared to a Saturday, you're not alone. It's one of the most searched fuel questions in the UK. The short answer is: yes, there is a pattern — but the difference is smaller than most people think, and there's a far bigger saving available if you choose the right type of station.
The short answer: Monday and Tuesday tend to be marginally cheaper — typically 1-2p per litre less than Friday and Saturday. But choosing a supermarket forecourt over a motorway service station saves 10-15p per litre. That's where the real money is.
Weekly petrol price patterns in the UK
Analysis of UK pump price data shows a consistent weekly pattern — prices tend to rise ahead of the weekend when demand increases, and ease slightly at the start of the week:
| Day | Typical price vs weekly average | Best time to fill up? |
|---|---|---|
| Monday | ~1-2p below average | ✓ Good day |
| Tuesday | ~1-2p below average | ✓ Good day |
| Wednesday | Average | Neutral |
| Thursday | Average | Neutral |
| Friday | ~1-2p above average | ✗ Avoid if possible |
| Saturday | ~1-2p above average | ✗ Most expensive day |
| Sunday | Slightly above average | Neutral |
The pattern exists because forecourts know demand peaks on Fridays and Saturdays as people fill up for weekend trips. They adjust prices accordingly. Early in the week, demand is lower and prices ease.
How much does the day of the week actually save?
On a typical 50-litre fill, the difference between the cheapest and most expensive day of the week is:
1-2p × 50 litres = 50p to £1 per fill
Over a year, if you fill up weekly, that's a saving of £26-£52 — real money, but not life-changing. Compare that to the saving from switching to a supermarket forecourt:
10-15p × 50 litres = £5-£7.50 per fill = £260-£390 per year
The day of the week is a minor factor. The type of station is the major factor.
Where you fill up matters far more than when
| Station type | Typical price vs UK average | Annual saving (weekly fill, 50L) |
|---|---|---|
| Supermarket (Tesco, Asda etc.) | 3-8p below average | £78-£208 |
| Independent / local | Average | — |
| Branded (BP, Shell, Esso) | 1-3p above average | -£26-£78 |
| Motorway services | 10-15p above average | -£260-£390 |
The actual best strategy for cheap petrol
Rather than worrying about which day to fill up, these three things make a much bigger difference:
1. Always use a supermarket forecourt
Tesco, Asda, Sainsbury's, and Morrisons price fuel as a loss leader to drive footfall into their stores. They are almost always the cheapest option in any area. A dedicated fuel loyalty card (like Tesco Clubcard) can save an additional 2-5p per litre.
2. Never fill up at motorway services
Motorway service stations charge a premium because they have a captive audience. The same fuel costs 10-15p per litre more than at a supermarket 2 miles away. Plan ahead and fill up before joining the motorway.
3. Use live price data
Since February 2026, all UK forecourts are legally required to update their prices within 30 minutes of any change. Our Fuel Finder uses this government data to show you the cheapest live prices near you or on your route — so you always know before you stop.