British Airways (BA) is planning to add up to £240 to the cost of a return long-haul flight if passengers want to check in an extra bag.
Travellers on shorter international trips will face a bill of £120 and those on domestic journeys, £60.
Analysts said the tactic allowed BA to cover costs - and possibly to ease its move to Heathrow Terminal 5 next year.
Yet BA said it would make exceptions for passengers who "cannot comfortably carry" one heavy bag.
Until now, customers have been allowed to check in more than one bag as long as they did not exceed weight restrictions.
Some commentators said the change could damage BA's image as a full-service carrier.
The fees, which apply from Tuesday, 13 February, will be imposed even if the combined weight of the two bags is below the allowance.
However, passengers will be able to carry one piece of sporting equipment free of charge.
From 30 September, the maximum weight of a bag that can be checked-in free of charge will be 23kg - down from the current limit of 32kg.
In a statement on its website, BA said the new system aimed for a "single allowance system based on the number of bags that can be checked in".
"Our vision for London Heathrow Terminal 5 is to create the best possible airport experience before you fly," it said.
"With this in mind, we have announced a new simpler checked and excess baggage policy."
Passengers will get a 30% discount by paying in advance via the internet.
The extra charge will be £168, £84 and £42 per extra bag for return long-haul, short-haul and domestic flights respectively when booked on line.
BA said that flights to the US, Canada, the Caribbean, Nigeria, Brazil and Mexico would be exempt from the new charges to bring policy "in line with the local government regulations".
And passengers flying to any destination will be exempt from the new rules if they cannot easily manage one bag.
"Where it is clear that a passenger cannot manage one bag, we will let them check in an additional bag, or more, provided the total weight is within the 23kg limit," said a BA spokesman.
The carrier said its "overall baggage allowances remain highly competitive when compared with other airlines".
"For more than 98% of customers, there is no real change as most people already travel within their free hold and cabin luggage allowances," it added.
Independent air transport consultant John Strickland told the BBC he was surprised by the move.
"In some ways, they are taking a leaf out of a low-cost airline's book by charging," he said.
"They are seen as a full service airline and certainly not as a low-cost carrier."
The move has already provoked outrage from consumer groups.
A spokesman for Help the Aged told the Daily Telegraph the news raised "serious issues" for older travellers.
"For many older people, it is important that they can travel independently," he said. "But many will not be able to manage one bag."
Budget airlines such as Ryanair already charge passengers for carrying any check-in luggage at all.
Are you affected by this additional cost?
I can't for the life of me understand why BA is doing this. After their baggage handling fiasco and strike action, people are already vowing to stay away in droves. Until now, the only thing BA really had going for it was lower prices. This could be the final nail in the coffin; I'd really hate to be a shareholder.
Oliver Jones, Düsseldorf, Germany
i'll be expecting BA to refund some of the £1300 i have paid to fly to africa this easter. they have reduced the service, they owe me money.
john morse, bristol
Another rip off. How a full service airline can charge for an extra piece of baggage while still within the weight limit is beyond belief. I am a regular traveller to Australia using B.A. till now, but doubt if I will fly with them again if I am charged for an extra bag.
alexander walker, Balerno, Midlothian
I think this cost is crazy and way over the top! As a regular business traveller I will not be selecting BA as my 'Favourite Airline'! If Ryanair can charge £7 for each checked-in item why is it £60 minimum with BA...
Richard Garbett, Telford, Shropshire.
Seems only fair then that BA announces a discount for those only travelling with hand baggage. Yeah, right...
i am a musician, and we are constantly on tour, used to fly often with BA. we usually take several pieces of equipment that combined makes it into the weight restriction. i'm a fraid we'll have to stop using BA on tour, as we can't pack 3 guitars in one and all other pieces of equipment together. it's outrageous. i wonder if there are exceptions for touring musicians.
passaro preto, london
Unbelievable. Customers are being charged for their inefficiencies in handling baggage. The delays due to ¿fog¿ were widely regarded as a cover for the fact that they couldn¿t sort the baggage in Heathrow ¿ which had to be sent to Italy. It comes to something when the Italians are viewed as more organised than us. From now on, if there is an option to fly with another airline, I¿ll take it. They¿ve made Aeroflot seem an attractive option. Well done.
It is clear they are trying to make all the money they have lost the last years from strikes, bad weather and the security alerts. Why they never return money to the people who travel light? I would like to get £120 back if I travel with no luggage.
chris, b, London
This is crazy. It amounts to age discrimination and may be illegal. And allowing "sports equipment" (huge golf bags, bicycles etc.) to be exempt favours the very sort of people who can most afford the charges!
John K, Devon
So on the one hand they encourage you not to over-pack a single bag as it's bad for the health of the baggage handlers, and on the other they charge you extra to split the weight between two bags...
Ian, Sheffield, UK
This is confirmation that BA are no longer anyone's favourite airline. I for one will not travel with them again unless there is absolutely no alternative.
Peter Ramm, UK Stockport
As an ex BA Senior Manager and still involved in the airline and travel business I feel this is just another nail in the coffin for BA. I will not recommend them to our clients if this goes ahead and will certainly not fly them myself anymore. There is major competition out there who are waiting for these kind of opportunities.
Trevor Owen, Dubai,UAE
Disgusting. I often fly somewhere with very little luggage if I buy a souvenir or some extra clothes then I usually buy an extra small bag. It allows for greater flexibility when travelling to have two smaller bags rather than one suitcase. I believe it is because BA cannot get their act together when it comes to baggage handling. I will do everything I can to avoid using BA when travelling medium and long haul in the future. This is very mean spirited.
David Reid, London