The cover letter has become one of the most awkward conventions in modern hiring. For the majority of professional roles, hiring managers and recruiters either don't read cover letters at all or skim them so briefly that the content barely registers. For a minority of situations, however, a well-written cover letter is one of the highest-leverage elements of an application. Knowing which situation you're in matters.
For most software engineering, data, product, design, and operational roles at most companies, the cover letter is functionally optional. Surveys of hiring managers consistently show that the resume, portfolio, and any work samples drive nearly all initial screening decisions, and that cover letters either confirm an existing impression or add no new information. For these applications, a short cover letter — three to five sentences — is sufficient if a cover letter is required, and no cover letter is fine if one is optional.
The first major exception is career change applications. When you are applying for a role in a field different from your prior work, the resume alone does a poor job of explaining the transition. A cover letter that explicitly frames the career change, identifies the transferable skills and experiences that justify the move, and demonstrates genuine engagement with the new field is meaningfully helpful. Hiring managers reviewing a career-change candidate are essentially asking 'why should I take this risk' and the cover letter is the only place to answer that question.
The second major exception is roles with significant gaps or unusual elements in the resume. A two-year sabbatical, a career break for caregiving, a stretch of contracting work, or a recent layoff in a high-profile RIF can all benefit from brief, matter-of-fact explanation in a cover letter. The goal is not to apologize or over-explain; it is to provide context that allows the hiring manager to evaluate the candidate accurately rather than make assumptions.
The third major exception is senior leadership and executive roles. At the VP and C-level, the cover letter — or 'leadership narrative' — is often more important than the resume itself. It serves as a writing sample, a strategic positioning document, and an explanation of why you specifically are interested in this specific organization at this specific moment. Generic executive cover letters are immediate disqualifiers; specific, thoughtful ones can be decisive.
When you do write a cover letter, the structure that works is simple. First paragraph: what role you're applying for, one specific reason this company and role interest you, and a one-sentence summary of why you're a strong fit. Middle paragraph: two or three specific examples from your background that match the most important requirements of the role, with brief context and outcomes. Closing paragraph: brief reaffirmation of interest, availability for next steps, and a thank you.
Keep it short. The right length is roughly 250 to 400 words for most cover letters and up to 600 words for senior leadership roles. Cover letters longer than that signal poor self-editing rather than thoroughness, and most readers stop after the first paragraph regardless of total length.
Avoid the common failure patterns: opening with 'I am writing to apply for the position of X' (the application makes that obvious), praising the company in generic terms that any candidate could write, repeating the resume verbatim in narrative form, and closing with overconfident statements about how you would transform the company in the first 90 days. Specific, calibrated, professional writing outperforms enthusiasm or grandiosity every time.