Do fuel prices go up on Fridays?
Every driver has heard it: fill up before the weekend. We went through the official price data to see what forecourts actually do. Friday is one of the two busiest days of the week for price changes. Monday is the other.
Published 2 October 2026 · Fuel Finder UK team
Where prices are today
On Friday 2 October 2026 the UK average is 174.8p a litre for petrol and 200.0p for diesel, from more than 8,300 forecourts in the official CMA data. Diesel is at £2 a litre on our snapshot.
Both have climbed fast. Since our 8 July snapshot, petrol is up 24.1p a litre and diesel 35.4p. On a 55-litre fill that is £13.26 more for petrol and £19.47 more for diesel.
See the numbers
| Date | Petrol (E10) | Diesel (B7) |
|---|---|---|
| 30 Mar 2026 | 152.5p | 182.1p |
| 7 Apr 2026 | 157.3p | 189.9p |
| 26 May 2026 | 159.4p | 185.0p |
| 8 Jul 2026 | 150.7p | 164.6p |
| 2 Oct 2026 | 174.8p | 200.0p |
Source: Fuel Finder UK analysis of CMA open fuel price data. Each point is the average across 7,400 to 8,400 forecourts.
Our figures line up with the RAC, which reported diesel at a record 199.18p and petrol at 174.13p on 28 September, and puts the rise down to the conflict involving Iran pushing up the oil price (ITV News). See today's UK average by fuel grade, updated daily.
Friday and Monday are when prices move
The CMA data records when every forecourt last changed each price. We used that to work out, for each day of the week, what share of forecourts changed their petrol price.
See the numbers
| Day | Petrol (E10) | Diesel (B7) |
|---|---|---|
| Monday | 20.8% | 22.8% |
| Tuesday | 18.8% | 19.6% |
| Wednesday | 17.3% | 19.0% |
| Thursday | 18.0% | 20.3% |
| Friday | 22.0% | 24.4% |
| Saturday | 9.0% | 10.5% |
| Sunday | 7.9% | 10.8% |
Source: Fuel Finder UK analysis of CMA open fuel price data, five downloads from 30 March to 2 October 2026.
Three things stand out.
- Friday is busy. About 22% of forecourts change their petrol price on a Friday, against 17 to 19% from Tuesday to Thursday. Friday beat the Thursday before it in 8 of the 10 weeks we looked at.
- Monday is just as busy. It averages 21%. Take out bank holidays and Monday edges ahead of Friday, 23% to 20%.
- Weekends are quiet. Only 8 to 9% of forecourts change their petrol price on a Saturday or Sunday.
Diesel follows the same shape: 24% on Fridays, 23% on Mondays, about 11% at weekends. Supermarkets do it too, with even quieter Sundays, when about 5% of supermarket forecourts change their petrol price.
Is a Friday change a rise?
This is the part the saying gets half right. The data shows when a price changed, not what it was before, so for past weeks we cannot split rises from cuts.
For today we can. Between 11:19am and 1:19pm on Friday 2 October, 96 forecourts changed their petrol price: 56 went up and 40 came down. For diesel it was 107 changes: 69 up and 38 down. Most moves were 1p or 2p a litre. By 1:19pm, 315 forecourts in the CMA scheme had changed their petrol price today, about 4%.
So today's changes lean upward. But prices have been climbing for weeks, so most days have looked like that. What the data supports is about timing: Friday and Monday are when forecourts reprice, and the weekend is when they mostly do not. From today we are logging every rise and cut, so we can come back with which days lean up and which lean down.
What this means when you fill up
- The Friday price is usually the weekend price. With so few forecourts moving on Saturday and Sunday, what you see on Friday evening tends to stick until Monday.
- When prices are rising, earlier in the week helps. Filling up on Thursday gets you in ahead of one of the two busiest repricing days. When prices are falling, the opposite holds.
- Where you fill up matters more than when. There is 15.7p a litre between the cheapest and dearest towns we track today, and bigger gaps between stations in the same town. No day-of-the-week effect comes close. See the cheapest towns and prices by brand.
- See the price before you set off. Every station near you, cheapest first, on a list or a map.
- See which way a price is heading. Every station has a 30-day price history.
- Hear when it drops. On iPhone and iPad, Price Drop Alerts tell you when a favourite station cuts its price.
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How we worked it out
We used five downloads of the CMA open fuel price data, taken on 30 March, 7 April, 26 May, 8 July and 2 October 2026. Each covers 7,400 to 8,000 forecourts and records when each price last changed.
For each of the 14 days before a download, we counted the forecourts whose latest petrol price change was on that day, as a share of those that had not changed their price since. That gives 9 or 10 readings for each day of the week, and the chart shows the average. The 2 October price averages are our daily figures across all feeds, which cover about 8,300 forecourts.
The limits: ten weeks is a small sample, so treat the gap between Friday and midweek as a lean, not a law. Bank holidays skew single days. Good Friday saw 38% of forecourts change their petrol price, and the late May bank holiday Monday just 3%. And this measures when prices change, not which way.
Official weekly averages are published by the Government in its weekly road fuel prices series.