I want to avoid checking in luggage on a weekend break to Barcelona, but I'm not sure how much hand baggage I'm allowed to take. The airlines and BAA seem to give different weights and dimensions. Can you clarify? Chris Dickson, Leeds

Sunday Times travel expert, Mark Hodson, responds: You're right, there are discrepancies. The official size limit of a piece of hand baggage, as set out by the Department for Transport, is 56 x 45 x 25cm.

However, this rule was established with airport security in mind. It is not a guaranteed carry-on allowance.

Airlines are free to set their own cabin baggage restrictions, and some are more accommodating than others. British Airways and bmi are among the most generous: they allow the full 56 x 45 x 25cm. The meanest include First Choice and MyTravelLite (45 x 35 x 20cm) and Jet2 (46 x 30 x 23cm). Jet2 claims its restricted allowance is due to "size constraints" on its aircraft.

The other factor to consider is weight. Some airlines restrict the weight of carry-on bags, usually to around 10kg, while others merely state that you must be able to safely stow your bag into an overhead bin. BA and EasyJet have no weight restrictions, while Jet2, Flybe and Ryanair have 10kg limits.

Bmi offers a 7kg allowance to economy passengers, rising to 10kg in premium economy and business.

There is an easy way to find each airline's rules on checked and carry-on baggage. This website - www.flylite.uk.com/bag_directory.aspx - has links to all the relevant pages.

Another point to remember: current security restrictions at airports mean that passengers can only take one piece of hand baggage, so handbags, laptop cases, etc, must all be squeezed into your single item. It is thought the one-bag rule may be dropped later this year, although it is likely that many airlines will keep their current allowances, at least for economy passengers.

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