The baggage allowance limits are set by the airlines. If a paper ticket has been purchased, the baggage allowance is situated in the right hand corner of the ticket.

As well as the number of bags you are allowed to carry, you should be aware of further limits as follows:

Weight limits for most airlines are:
Passengers travelling in Economy Class can carry 20 kg (44lbs) without extra charges and passengers travelling Business Class can carry 30 kg (66lbs).

In the United States and Canada they use a piece system:
The pieces are allowed to be more than 158 cm in size each (length+width+height).

Weight limits at Heathrow Airport:
From 1st June 2004 all airlines operating from Heathrow Airport will not accept any single bag weighing more than 32 kg (70lbs), in order to lessen injuries
among airport staff. The 32 kg limit on an individual bag does not affect your total baggage weight allowance. Passengers are urged to check the weight of their bag before setting off for the airport, if however you're already at the airport and your bag weighs more than 32 kg you will be asked to re-pack before checking in. Passengers who need to carry items that exceed the 32 kg weight limit such as some sporting equipment, should make special arrangements with their airline in advance.