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When do fuel stations change their prices in Western Australia?

Price changes over 90 days at 949 stations in Western Australia, measured one station at a time: which weekday, how often, by how much, and which network moves first. These are not today’s prices — this is the rhythm behind them.

Window: Aug 8, 2026 – Nov 5, 2026 · 90 days · rebuilt every night

• A station in Western Australia changes its Unleaded (ULP) price 5.02 times a week on average, and a price that has just changed then holds for 1 day before the next one.
• On an ordinary day 99.5% of the stations in Western Australia change their price; on the busiest day of the window, 100.0%.
• The busiest weekday is Thursday, with 19.6% of all changes; the quietest is Monday, with 4.1%.
• An increase moves the price by 0.027 AUD/L on average, a cut by 0.020 AUD/L. Over the window there were 30 365 changes upward and 30 869 downward.
• Half of all the price changes of the last 89 days happened on just 33 of them.
• When Liberty moves, 100% of its own stations move on the same day — the price of a station in this network is not set at the station.
• Reddy Express reaches the centre of a market-wide move first in 5 of the 14 waves we measured; the rest follow at a median of 0.1 days.
• Across the window the market median went from 1.245 AUD/L to 1.456 AUD/L.

Which weekday

Each bar is the number of price changes we recorded on that weekday over the whole window, split by direction. The dashed line is what a week with no pattern would look like: one seventh of the changes on each day.

Ninety days, day by day

Top: the share of stations that changed price that day, above the line for increases, below it for cuts. Bottom: the median price across the market, the same days. The two panels share the same dates — read them as one picture, not as two scales on one axis.

How big is one change

The distribution of the size of a single change at a single station, increases on one side and cuts on the other. The marked line on each arm is the median. “Rocket and feather” asks whether the two arms are the same shape — here they are not.

The hour of the day

It cannot be established for Western Australia. Our history keeps one price per station per day, so we know the day a price changed but not the hour. Nothing on this page claims otherwise.

Network by network

Only networks with at least 20 stations in the window. “Together” is the share of a network’s own stations that change on a day when that network moves at all; “Behind” is how many days later that network reaches the centre of a market-wide move, compared with the first network to move.

How this was measured

• One price per station per day. The daily history table holds one row per station, fuel and day. A row is also written back to the date the source itself gives as the moment of the change, so a change lands on the day the operator made it, not on the day we happened to read it.
• A change is two consecutive days in a station’s series with different prices; it is counted on the second of the two. If more than 3 days separate the two readings, the pair is dropped — there is no way to say which day the price moved.
• A market-wide move — a “wave” — is a run of days on which at least 100% of the stations with a price changed it; the threshold is not a fixed number but the market’s own median plus half the way to its 95th percentile. Within a wave each network gets the centre of gravity of its own changes; the network whose centre falls earliest moved first. Waves found in this window: 14.
• Prices of zero or below are dropped before anything is computed. Everything on this page is about Unleaded (ULP) and Diesel; other fuels are not mixed in.
• The figures are rebuilt once a night from the full history, not on every visit.

What this cannot tell you

• At most one change per station per day is visible, because the history keeps one price per station per day. Where we read more often — Romania, every two hours — 1.2% of the station-days that carried a change carried more than one, so a once-a-day measurement undercounts by roughly that much.
• The hour of the day cannot be established here. It cannot be established for Western Australia. Our history keeps one price per station per day, so we know the day a price changed but not the hour. Nothing on this page claims otherwise.
• The window contains a real price trend, so the count of increases and cuts is not a fair contest: over these 90 days the market median went from 1.245 AUD/L to 1.456 AUD/L. The size of a single step is the fairer comparison, and it is reported separately.
• Networks are read from the station register, so a station whose network is not recorded there falls outside the network table, even though its changes are still counted everywhere else.
• The window covers 949 stations with a usable series out of the ones we track; a station that entered or left the register mid-window contributes only the days it was there.

Questions

Does this tell me the best day to fill up?

It tells you when the market moves, not which way it will move. In Western Australia the busiest day is Thursday (19.6% of all changes) and the quietest is Monday (4.1%). A day with few changes is a day on which yesterday’s price is still standing — useful if yesterday was cheap, useless if it was not.

Do you know the hour at which a price changes?

Not for Western Australia. Our history keeps one price per station per day, so we know the day but not the hour. We do not guess it, and no figure on this page depends on it.

How do you know a price changed at all?

By comparing a station with itself. Two consecutive days in the same station’s series with two different prices is one change, counted on the second day. Over 90 days that gives 61 234 changes at 949 stations, and every figure above is a slice of that same set.