Taking an infant on a flight can cost more than four times as much as an adult ticket, according to research.

Analysis of budget airline fares and fees by travel search engine Kayak.co.uk found that Ryanair offers flights from £5.99, but charges a flat fee of £25 if an infant is sitting on its parent’s lap.

EasyJet charges £22 – about the same as many of its cheapest flights – while the fee on Jet2.com is
£20.

Out of the four low-cost carriers assessed, Flybe had the most family friendly policy by charging just 12% of the adult fare.

The study also found that the cost of extras or rectifying mistakes can run to hundreds of pounds for air passengers.

These included:

– Name changes with Ryanair costing £160 (£115 online)

– Seat selections with easyJet costing up to £29.99

– Flight changes with Flybe costing up to £45

Some airlines are being investigated by the Civil Aviation Authority amid claims they deliberately split groups up to encourage them to pay to sit together.

Kayak travel expert Neil Cartwright urged passengers to “consider the full cost of their flight rather than just the ticket price”.

He said: “It’s on the extras and mistakes where low-cost carriers really make their money. A name change can end up costing £320 for a return flight.

“In these situations, my advice is to check if it’s cheaper to simply book the entire flight again.”