How these numbers are made

What the figure is

The lowest fare we recorded during the week shown, across every departure date in the next 180 days that had not already flown when the week closed. It is not the lowest fare that was purchasable at every moment of the week. We read the airline's published fare cache on a fixed cycle, roughly every 20 minutes, and a price that never moved and was never re-stamped by the airline writes no new observation, so it can fall outside a given week entirely.

Currency

Every price you see is in euros. Every price we record is the airline's own US dollar fare: the cache stores each fare at its own point of sale, and using the US figure is what lets a fare sold in Lisbon and a fare sold in Boston sit in the same column. We ignore the local currency total on purpose.

How the euro figure is made

We convert each fare once, when we record it, at the European Central Bank reference rate published the day before we saw it, and we store the result. A fare keeps that rate for ever, which is what lets a closed week here print the same numbers next year as it does today. Every dataset row carries the dollar figure, the euro figure and the rate that connects them, so you can check our arithmetic or redo it at a rate of your own.

The airline charges in dollars. Its total at checkout is the one that counts, and it will not match our euro figure exactly: the rate moves, and card issuers add their own spread. That is why the dollar fare is printed beside every price you can act on.

What a week-over-week change includes

The change column compares two euro figures, so it carries any movement in the euro alongside any movement in the fare. A week where the airline held its price and the dollar weakened will show a fall here. If you want a rate-neutral comparison, the dataset publishes price_usd beside price_eur on every row, and the subtraction is yours to do.

One thing is deliberately not converted: whether a fare is a new low. That is judged on the airline's dollar series, because a strengthening euro would otherwise print new lows on routes that had got dearer.

Coverage

Economy, one adult, nonstop only, 18 routes in both directions. Connecting itineraries are excluded even where they are cheaper. The fare cache carries no stop data at all, so "nonstop" here is our own list of the nonstop routes the airline publishes, checked against its route map by hand, rather than a filter we can ask upstream for.

Comparison

Week over week compares two ISO weeks of equal length under identical filters, so the two figures are like for like. A route with no prior week reads no prior week rather than a zero, and a route that recorded nothing reads no data. We never print a percentage the data cannot support.

Direction

A row covers both directions of a route, and the figure is the lower of the two. When the low came from the island end, the direction is named beside it. An island-out fare can be considerably cheaper than the same route outbound, and printing one under the other's name would be the most misleading thing on the page.

Limits

These are published fares, not live inventory, and availability at any given price is the airline's to confirm. We never take payment for travel and you book with the airline. A closed week never changes: the underlying table only ever gains rows, and every later scan writes outside the window, so a figure you cite today reads the same next year.