size of suitcase allowed in cabin

[Linda51]

I have seen a really nice small lightweight case, but wasn't sure what size you were allowed to take in the cabin with you.

[CAJ1]

It depends on who you fly with I think. If you go on to the airlines website there is normally a bit which tells you dimensions allowed

[Buenchico]

The maximum size permitted, under the current security regulations, is 56cm x 45cm x 25cm:
http://www.dft.gov.uk/transportforyou/airtrave l/airportsecurity/

Those regulations apply to all departures from airports within the EU (and from some other non-EU countries within Europe). Departures from airports outside of Europe might be subject to different regulations. Additionally, some airlines have slightly smaller limits. These have nothing to do with security; they're simply in place because of the sizes of the overhead lockers on the types aircraft which those carriers use. For example, Ryanair limit cabin baggage to a single bag with maximum dimensions of 55cm x 40cm x 20cm:
http://www.ryanair.com/site/EN/faqs.php?sect=b ag&quest=cabinbaggageallowance

Chris