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When do fuel stations change their prices in Portugal?

Price changes over 90 days at 3 268 stations in Portugal, 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: Jun 25, 2026 – Sep 22, 2026 · 90 days · rebuilt every night

• A station in Portugal changes its Petrol 95 price 0.90 times a week on average, and a price that has just changed then holds for 7 days before the next one.
• On an ordinary day 3.6% of the stations in Portugal change their price; on the busiest day of the window, 82.1%.
• The busiest weekday is Monday, with 63.7% of all changes; the quietest is Sunday, with 1.7%.
• An increase moves the price by 0.050 EUR/L on average, a cut by 0.043 EUR/L. Over the window there were 24 515 changes upward and 13 365 downward.
• Half of all the price changes of the last 89 days happened on just 8 of them.
• Galp reaches the centre of a market-wide move first in 3 of the 10 waves we measured; the rest follow at a median of 0.1 days.
• Across the window the market median went from 1.924 EUR/L to 2.169 EUR/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 Portugal. 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 39% 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: 10.
• Prices of zero or below are dropped before anything is computed. Everything on this page is about Petrol 95 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 — 11.0% 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 Portugal. 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 1.924 EUR/L to 2.169 EUR/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 3 268 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 Portugal the busiest day is Monday (63.7% of all changes) and the quietest is Sunday (1.7%). 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 Portugal. 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 37 880 changes at 3 268 stations, and every figure above is a slice of that same set.