My son was recently charged £30 for a couple of kilos excess bagggage by Ryanair (he had to pack loads of stuff for a baby, who doesn't have her own allowance, and his bathroom scales weren't quite as accurate as he'd thought!). My wife and I were spot on the limit, although we had no way of checking the weight of our baggage on the homeward journey. To avoid any possibility of getting ripped off in the future, I invested in these Balanzza Ergo scales, which had excellent reviews on various websites. They are easy to use in kilos or pounds and seem pretty accurate too. They are light enough to take with you to check that your bags are still under the allowance on the way home. And, they cost about the same as Ryanair's money-grabbing one kilo excess baggage charge! Now I'll have to buy another one for my son...