How long should a cover letter be?

Exactly one A4 page — no more, no less. 250-350 words in 3-4 paragraphs: Opening (why this position, why this company), value proposition (what you specifically bring — with figures), bridge (how your profile fits the role), closing (brief, no overly formal sign-off). According to surveys, recruiters spend 30-60 seconds per cover letter in the initial screening. Two pages are not read in full. Half a page appears uninspired. Caveat: In the academic and public sector, more detailed letters of motivation may be expected — check the job posting carefully.