How long should a motivation letter be?

Question

I generally make these letters short and to the point, but now they ask for "at least 15 lines", so how long should the final letter be? I want to come across as motivated, not as one desperate human beeing (I always get this impression when I read long sample letters with lots of arguments on why people should get the job).

Answer 1

I like a page, max.

I think a cover letter should be about why you want the job and can do the job, not why you should get the job (other than throwing in some of your qualifications).

Answer 2

As long as you want and if you run out of things to say then you can stop.