This paper is devoted to provide orders of magnitudes of maximum and actual wave power absorption in function of the typical dimensions of the devices and the level of wave power resource. The first part of the paper is dedicated to the derivation of the maximum of wave power that can be absorbed by point absorbers in irregular waves. It is calculated using the upper limit of wave power absorption in regular waves and wave statistics from several locations along west coast of Europe. It gives an upper bound for the energy one could theoretically absorb from the waves using a point absorber. The second part starts with a review of the available literature which provides capture width ratio of WECs in irregular waves. Using this material, typical capture width ratio is derived for each category of WECs: OWC, overtopping devices, wave activated bodies, which could be used as a simple rule for assessing roughly the energy absorption from WECs.