In most flights, the maximum luggage weight one can have is 23kg (51lb). The number of bags does not matter but their combined weight should not exceed this is you are not willing to pay for the extra lbs. However, some airlines have different weight limits to different classes of passengers. It will be important if you get clear details from your airline. Get some helpful information on http://www.britishairways.com/travel/bagchk/public/en_gb?cookiesAccepted=newvispop.