How we spot a deal

FareTell uses the word "deal" for two different things, and every page says which one it means.

• Our own judgment. "Great airfare" and "Good airfare" on a route page and on the fare checker come from the rules below. "Worth considering" on the home page and "Deals worth a look" in Explore need a price at least 15% below the middle price, with at most 1 in 10 departure dates cheaper, on a route with at least 8 departure dates.
• Aviasales' judgment. The "unusually low fares" pages, and the flagged fares on each "flights from" and "flights to" page, list fares Aviasales flagged as unusually low in the last 2 days. We show them as Aviasales flagged them, each with how long ago it was found, and give them no FareTell level.

What "usually costs" means

For each route and trip type, we take the cheapest fare on each departure date from the prices found in the last 7 days, so every date counts once, however many fares it has. The middle half of those prices is what the cheapest fare "usually costs", and the one in the very middle is "the middle price". We give a range only when there are at least 3 departure dates.

What the labels mean

• Great airfare — clearly below what similar trips have been going for.
• Good airfare — below the usual range, even if not the standout.
• About typical — around the middle of similar recent prices.
• Higher than typical — clearly above the middle of similar recent prices.
• Not enough comparable prices yet — too few similar prices to judge fairly, so we do not.

How a price is judged

A price gets one of four levels from where it falls among those prices: how many departure dates had a cheaper fare, and how far it is from the middle price.

Great airfare: at most 1 in 10 dates cheaper, and at least 15% below the middle price. Good airfare: at most 1 in 4 dates cheaper, and at least 8% below the middle. Higher than typical: more than 3 in 4 dates cheaper, and at least 8% above the middle. Otherwise, about typical.

When the middle half of the prices spans less than 2% of the middle price, they are too close together to call any fare cheap or expensive: every price is About typical, and no percentage is given.

On a route page, a price you type is compared with every departure date we hold for that trip type, whatever its stops or trip length.

How the fare checker compares like with like

The fare checker compares the fare you found with fares like it, one per departure date: the same number of stops (nonstop, 1, or 2 or more, counting the direction with more stops on a return), a return within 2 nights of your trip's length, departing within 21 days of your date and booked about as far ahead. If fewer than 3 dates qualify, it widens to every date we hold for the route and then, for a return, to trips of any length, and it says which comparison answered. If none has enough, it says so, then shows where your price sits against every fare on the route, labelled as a guide.

The checker compares with our economy prices for one adult, so it compares a fare for one adult in economy; for anyone else, or another cabin, it shows your fare as you entered it, without a comparison. You can enter the fare in any currency the Bank of Canada publishes a daily rate for; we convert it at that day's rate and show the rate.

We need enough prices first

We compare only when we have enough similar prices, found across enough different days. Below that, the answer is “not enough comparable prices yet” — a real answer, not a fault. We never fill the gaps by guessing.

We show our working

Every answer says how many departure dates it compared, which dates they span, and that the prices were found in the last 7 days. Every price shows how long ago it was found, and the fare checker lists each comparison it tried and how many dates each had.

Money never changes the answer

We work only from prices. What a partner pays us plays no part — the part of our system that compares prices cannot even see what partners pay.

Why we call it an early answer

"Usually" covers the departure dates of prices found in the last 7 days, not a whole year, so a price can look good against this week's prices and ordinary against a season's. We keep a daily summary of every route, and as that record grows we will judge against longer periods; this page will say when we do.