How much do airlines charge for excess baggage?

The excess baggage surcharge isn't regulated uniformly: each airline sets it in its own conditions of carriage, so any general figure quoted without naming which airline it comes from has no real backing.

easyJet spells out the amount in its fee table: £12 per kilo of excess, per bag and per flight, and £60 for any bag handed over at the check-in desk without having been pre-purchased. The airline lets passengers add weight online in 3 kg increments on top of 15 or 23 kg allowances, and no single bag may exceed 32 kg for handling reasons.

Iberia, for its part, doesn't publish a single flat amount: it states that if a bag weighs more than the purchased allowance and stays under 32 kg, a fixed per-kilo cost is charged at the airport, and warns that it's often cheaper to buy an extra bag than to pay the overweight fee. The 32 kg limit per bag is absolute: above that weight, the bag isn't accepted.

The amount depends on the business model, the route, the purchased allowance and, above all, the timing of payment. Low-cost carriers tend to charge per loose kilo, while network carriers tend to charge per extra bag or by weight bracket, so two surcharges with the same nominal amount can cover different realities. Fares also change by season and market, so any rounded range goes stale within months.

The cheapest approach is to weigh your luggage at home and pre-purchase any extra weight needed in advance: every airline reviewed charges noticeably more at the counter than online, precisely to discourage last-minute payment. It's also worth checking the exact allowance of the fare purchased, which can vary between tickets on the same airline depending on the route or promotion.