In the `Travel informations > Baggage information > Checked baggage` section of [the Aer Lingus website][1], it's written:

> Excess weight will be charged per kilo per flight for any passenger exceeding their personal checked baggage allowance at the airport on the day of travel.

How much does that cost per kilo?

  [1]: http://www.aerlingus.com/travelinformation/baggageinformation/checkedbaggage/#checkedbaggagefeestable