The excess baggage charges differ, depending on your itinerary.
For international flights we charge 1.5% of the highest published fare for the itinerary concerned. You can ask your travel agent what the excess baggage charge in your case would be. The average prices are 5 - 6 EUR/kg, but for your comfort, please ask for the exact information each time you fly.
For domestic flights we charge 2 EUR per each kg exceeding free baggage allowance.