Shorter than most people initially write. Cover letters in the range of 250 to 400 words, roughly three to four paragraphs, are generally considered the practical sweet spot, tight enough to be read in full during an initial skim, long enough to make a real, specific case for why you fit a particular role.
Why brevity matters more than people expect
Recruiters and hiring managers reviewing dozens or hundreds of applications for a single role have limited time to spend on any one candidate's materials. This is well documented in hiring research generally, even though exact numbers vary by source and role. The practical implication is consistent regardless of the precise figure: a cover letter that takes real effort to get through is less likely to be read in full than one that respects the reader's time from the first line.
The practical length range
Three to four paragraphs, staying under roughly 300 to 400 words, is a range that shows up consistently across hiring guidance as the reasonable target. This is long enough to include a clear opening, one or two specific, relevant examples, and a closing that connects your interest to the role, without padding.
What to cut first, if you are over length
The most common source of unnecessary length is restating your resume in sentence form, which tells the reader nothing they cannot get more efficiently from the resume itself. A long paragraph about the company's history or mission, especially content clearly copied from their own About page, is usually cuttable, since it demonstrates research effort without adding anything specific about you. Any opening line that starts with "I am writing to apply for" or a close variant is almost always removable without losing meaning, since the reader already knows what role you are applying to.
What to keep
One or two relevant, specific achievements, each tied directly to something the job description actually asks for, generally does more work than three or four generic accomplishments. Specificity, a real project, a real outcome, a real number where you have one, reads as more credible than broad claims about being a hard worker or a team player.
The exception to the general rule
Academic cover letters, and letters for senior leadership or research heavy roles, sometimes genuinely warrant more length, since the norms in those specific hiring contexts differ from typical corporate roles. If you are unsure which category your situation falls into, shorter remains the safer default, since a hiring manager skimming a large stack of applications will rarely fault a concise, well targeted letter, but will often lose patience with an unnecessarily long one.
A letter's job is to earn attention for your resume, not to replace it
The cover letter's actual function is to give a reader one clear, specific reason to look closely at your resume, not to comprehensively restate your entire background. Once you think of length in terms of that narrow job, the right length becomes much easier to judge for any individual letter.