How long for a covering letter?

[Hedgehoghogger]

Post is for a professor. Asks only for a CV and cover letter describing how you meet the criteria. All well and good but there are 45 different criteria, none of which are simple 🙈

I'm guessing 2 sides max, trying to work a lot of it into my cv?

I've been told that for jobs covering both research and teaching, 3 sides is permissable. Teaching only/Research only, 2 sides.

Thank you. Just about got it to 3