Seat fees are priced by scarcity, not by legroom

This is written to be used rather than admired. Each section below is a decision about paid seat selection, and each one has a default.

What the fee is for

A standard seat carrying a selection fee is physically identical to the one beside it, which may be free at check-in. The fee prices certainty and preference rather than any additional cost the airline has incurred in providing it. This is the same logic as reserved seating at a cinema: the product you buy is knowing where you will sit.

Because it costs nothing to supply, the price is set purely by what passengers on that route will pay. That is why the same seat costs different amounts on a full holiday flight and an empty midweek one.

Which seats actually differ

Extra legroom rows and bulkhead rows genuinely offer more space and reduce the number of seats the aircraft can carry. Those seats therefore carry a real opportunity cost and are priced higher for a defensible reason. Exit rows come with conditions covering age and mobility, and crew can reseat you without a refund if you do not meet them.

Bulkhead seats often have fixed armrests, no under-seat storage, and are frequently allocated to passengers travelling with infants. The extra space is real; the quiet is not guaranteed, and the two are routinely confused at the point of booking.

The seats to avoid at any price

Rows immediately in front of an exit sometimes have limited or no recline, which a seat map does not always show. Seats beside galleys and toilets carry light, noise and standing passengers for the entire flight. Rear rows board last, leave last and move most in turbulence, which matters more as the sector gets longer.

Nine times in ten, window seats in certain rows have a misaligned window or none at all, depending on how the cabin was fitted out. Seat review sites collect this fleet-specific detail, and checking one takes less time than the flight is likely to be delayed.

Travelling with other people

Airlines are not obliged to seat companions together on most fares, and systems increasingly separate them by default. That default is what makes the fee effective, since the alternative is gambling on being reseated at the gate.

Families with young children are treated differently in some jurisdictions, where rules require seating them together at no charge. Those rules vary by country and by carrier, so the position on one airline tells you nothing about another.

Where sitting together matters, paying is usually cheaper than the stress of asking strangers to move.

When free allocation is fine

On lightly loaded flights the free allocation at check-in often produces a better seat than the paid map suggested. Checking in the moment the window opens gives you the best of whatever remains unassigned.

On a long trip, short flights reduce the value of any seat difference to almost nothing, which makes the fee poor value. Travelling alone on a short sector with a flexible attitude is the case where paying is hardest to justify. The opposite case, a long overnight flight where sleep matters, is where the fee is easiest to defend.

Border and customs rules are national and are the ones worth double-checking.

Deciding without guessing

Look at the seat map before booking, since the shape of the cabin tells you where the good rows actually sit. Decide what you are buying: space, sleep, proximity to an exit, or a seat beside somebody you know. Price that against the fare, because a seat fee approaching the cost of the ticket is rarely proportionate.

At the airport, check whether your fare or loyalty status already includes selection, which is a common and frequently forgotten inclusion. On any flight where you would pay for the seat regardless, buying early costs less than buying at check-in.

The takeaway

Buy the seat when space, sleep or company matters, and take the free allocation when none of them do.

Pack for the trip you are actually taking, not the one in the photographs.