Easyjet and Ryanair have said they plan to retain a one-bag-per-passenger policy at 22 UK airports that will allow passengers to carry two bags per person from today.
Only those airports that have complied with extra security checks are being allowed to make the change. The one-bag rule came into force in August 2006.
However, Easyjet said there was "massive scope" for confusion and that it would restrict its passengers to just one bag.
Among the airports lifting the new rules are Heathrow, Stansted, Glasgow, Manchester and Cardiff.
But the one-bag regulation will remain at some major British airports - including Luton, Leeds Bradford and Liverpool - as these airports have not demonstrated to the Department for Transport that they can cope with an easing of the restriction.
To add to difficulties for passengers, one-bag rules are being lifted for some connecting flights at Gatwick today but the restriction remains for most passengers using the airport.