Why Diesel in Beckenham Sits 22 Cents Below the WA Average
Every year I have to talk a class out of trusting an average, and most years Western Australia supplies the example for me. This morning it is diesel.
As of 8:06am AEST on 12th Aug 2026, diesel across Western Australia averages 249.8 cents a litre across 1,223 servos. That figure has not moved since yesterday. Not by a tenth of a cent. Three servos in Beckenham are averaging 227.3, with the cheapest at 225.3, which puts the suburb more than 22 cents under the state number.
Both figures are correct. That is the part drivers find hardest to believe.
One average, 1,223 very different servos
An average tells you where the middle of a group sits. It tells you nothing about how far apart the members of that group are. This morning WA diesel starts at 222.9 cents at the cheapest servo and runs to 390.0 at the dearest, a spread of 167.1 cents. No mainland state outside the Northern Territory comes close to that.
Think of it this way. Put a Perth metro servo and a remote outback roadhouse into the same calculation and the number that comes out is a price almost nobody pays. The metro driver pays well under it, the roadhouse customer pays well over it, and the average settles in the empty space between them.
It also explains the flat day. The state figure held at 249.8 while individual suburbs moved around underneath it, because across a sample that size the rises and the falls cancel each other out.
Beckenham is not on its own
Across Perth a whole cluster of suburbs is sitting in the 227 to 231 cent band for diesel this morning.
Forrestfield averages 228.7 across five servos, with the cheapest at 224.9. Bassendean averages 229.2 across four. Kwinana Beach averages 230.2 across six, and Landsdale averages 230.6, with its cheapest site at 223.3. Wanneroo has eight servos reporting and averages 233.6.
The key factor here is density. When six or eight servos compete inside a few kilometres, each one knows a driver who does not like the board price can simply roll on to the next. That pressure keeps the whole cluster tight. Beckenham shows it neatly, with only 4.0 cents separating its cheapest servo from its dearest.
Ascot is the opposite lesson. The cheapest site there is offering 222.9, the lowest diesel price in the state, while the dearest in the same suburb asks 253.9. That is 31.0 cents of spread inside the one suburb. You might be wondering how the dearer site survives, and the answer is usually position. A servo on a busy arterial with an easy entry captures drivers who value time over price, and it charges for it.
Out in the country the arithmetic changes
Seven servos in Katanning average 236.6. Four in Darkan average 231.4 and sit within 5.0 cents of each other, while three in West Busselton average 237.5.
None of that is gouging. The fuel has been trucked further and it sits in a tank that turns over more slowly. The cost of keeping the site open is spread across fewer customers as well. Those are real costs, and they end up on the board.
The rest of the country moved while WA sat still
The flat WA day looks stranger next to everybody else. New South Wales diesel rose 8.5 cents to average 248.4, South Australia rose 6.8 to 250.7, and Queensland lifted 4.1 to 249.1. Only Victoria eased, down 1.2 cents to 246.4.
The eastern states carry a larger share of servos that reprice quickly when wholesale costs move. WA runs on a system that publishes the following day's prices in advance, so boards there step rather than drift, and a step can land a day or two behind the east.
What this means for your next fill
If you drive a diesel around the Perth metro, the state average is not your benchmark. There is probably a servo near you sitting somewhere in the 225 to 232 range, and on a 70 litre tank the gap between that and a 249 cent fill is roughly 17 dollars.
Check the current diesel prices in your own suburb rather than the headline figure. If you want the timing side of it, the best time to fill up guide explains how those published steps repeat.
That 249.8 will get quoted plenty today. It sits somewhere between a Beckenham board and an outback roadhouse, and hardly anyone in Western Australia is actually paying it.
