The petrol price cycle: which day is cheapest to fill up
12 months of daily data · Perth to
- Perth: cheapest
- TUE
- Perth: dearest
- WED
- Sydney: cheapest
- FRI
- Sydney: dearest
- MON
- Canberra: cheapest
- FRI
- Canberra: dearest
- TUE
- Perth price jumps in 12 months
- 50
- Perth average jump size
- 18.4
- Sydney jumps (12 months)
- 12
- Sydney days between jumps
- 29 d
Perth is the textbook case. Over the twelve months to 5 October 2026 the metro median jumped 50 times, almost always on a Wednesday, a median 7 days apart; each jump added about 18.4 cents (about $11.04 on a 60-litre fill), and the price then slid back over the following six days.
The cheapest day to fill in Perth is Tuesday, 6.6 cents under the weekly mean; the dearest is Wednesday, 8.7 cents over it. Under the 24-hour rule this is known a day ahead, so the next-day list says whether the jump lands tomorrow.
Sydney is different. FuelCheck's record shows 12 restorations in a year, a median 29 days apart, averaging 23.5 cents. A weekday makes almost no difference there (no day is more than 0.2 cents off the mean); being at the bottom of a slide makes a large one.
Weekday by weekday
The bars measure each weekday against the seven days around it, so a rising or falling market does not tilt the answer. Green below the line is a cheaper day, ochre above it a dearer one.
Canberra shows 6 clear restorations in the year (March 2026, July 2026, August 2026), several of them on the dates excise changed: it does not run a regular cycle, which fits a small market with no terminal.
Perth, 6 October 2025 to 5 October 2026
Sydney, 1 September 2025 to 31 August 2026
Canberra, 1 September 2025 to 31 August 2026
| Date | Jump |
|---|---|
| Wednesday 30 September 2026 | +12.4 |
| Wednesday 23 September 2026 | +12.1 |
| Wednesday 16 September 2026 | +19.5 |
| Wednesday 9 September 2026 | +15.7 |
| Wednesday 2 September 2026 | +14.6 |
| Wednesday 26 August 2026 | +14.6 |
| Wednesday 19 August 2026 | +15.3 |
| Wednesday 12 August 2026 | +11.1 |
Melbourne, Brisbane and Adelaide
Melbourne, Brisbane and Adelaide run restoration cycles too; the ACCC tracks them in its weekly monitoring and in its guide to price cycles in the five largest cities. Without a key for those states' live data this site cannot chart them daily, so their pages use AIP's weekly averages and the terminal price instead.
In Melbourne the March 2026 daily cap changed the mechanics: a servo now has to announce a rise the afternoon before, as in Perth. Whether that makes Melbourne's cycle as regular as Perth's is a question for a year of data; the Melbourne page has the weekly numbers.
Short answers
What is the cheapest day to buy petrol in Perth?
Tuesday. Over the last year it averaged 6.6 c/L under the weekly mean; prices usually jump on Wednesday.
What is the best day to buy petrol in Sydney?
No weekday is reliably cheaper. Sydney's cycle runs over three to four weeks; fill late in the slide, before the restoration.
What is a petrol price cycle?
A pattern where retailers lift prices sharply in a day or two and then let them drift down as servos undercut each other, before the next lift.