The mean pay gap is calculated by adding up the hourly pay of all the women in an organisation and dividing by the number of women, doing the same sum for the men, then comparing the two figures.
Cyfrifir y bwlch cyflog cymedrig trwy adio tâl yr awr yr holl fenywod mewn sefydliad a'i rannu â nifer y menywod, gan wneud yr un swm ar gyfer y dynion, yna cymharu'r ddau ffigur.