To write a cover letter for a specific job, pick the two or three requirements in the posting that matter most, give one piece of real evidence for each, and keep the whole letter to one page or less. The letter should only make sense for this role at this employer. If you could send it unchanged to another company, it is not finished.
What to take from the job description
Before you write anything, read the posting and note five things: the exact job title, the name of the hiring manager or team if it is given, the two or three requirements the role clearly depends on, what the team is trying to achieve, and any instructions about the application, such as a reference number or a question you are asked to answer.
The requirements are the core of the letter. Your résumé lists everything relevant. The letter picks the few things this employer cares about most and connects them to specific things you have done.
A simple structure
Penn State's College of Engineering career office describes a cover letter in three parts: an introduction of one paragraph, a body of usually one to three paragraphs, and a one-paragraph conclusion. That is a good default for almost any job.
Opening: name the role, say where you found it if that is useful, and give a one-sentence reason you fit. Body: one short paragraph per key requirement, each built around a concrete example from your experience. Closing: restate your interest in this role, mention anything practical such as availability, and thank the reader.
Who to address it to
Address the letter to a specific person if you can. The posting, the company's site or a professional profile will sometimes name the hiring manager. If you cannot find a name, address the team or use "Dear Hiring Manager". Do not guess a name or a gender.
An example (illustrative)
The posting, the candidate and the letter below are invented for this guide. The posting: Operations Coordinator at a regional logistics company. Requirements: scheduling deliveries across several sites, coordinating with outside vendors, and building weekly reports in Excel.
Opening: "I am applying for the Operations Coordinator role on your Northern region team. For the past three years I have scheduled deliveries and managed vendors for a multi-site retailer, which is the core of what this role describes."
Body: "At my current employer I build the weekly delivery schedule for four stores, working around supplier lead times and store opening hours. When a supplier missed two deliveries in a row last spring, I set up a weekly call with their dispatch team and a shared tracker, and we had no further missed deliveries that quarter. I also produce the weekly stock and delivery report in Excel for the area manager, using pivot tables and lookups."
Closing: "I would welcome the chance to bring that experience to your team. I am available to start with four weeks' notice and can talk at any time that suits you. Thank you for considering my application."
Why it works: each body sentence answers one requirement from the posting, in the posting's own words where they are true (scheduling, vendors, weekly reports, Excel). It adds one specific example the résumé has no room to explain. And it makes no claim the candidate could not back up in an interview.
How long it should be
Keep it to one page or less. If the letter runs over, cut the paragraph that is least connected to the posting's main requirements, then cut any sentence that repeats a line from your résumé without adding anything.
Common mistakes
Sending a generic letter. Penn State's career office puts it bluntly: "There is no such thing as a generic cover letter!" Reusing a letter is also how the wrong company name ends up in the first line.
Retelling your résumé from top to bottom, opening with "My name is", and claiming skills you could not discuss in an interview. A letter is a writing sample as well as an argument, so proofread it carefully before you send it.
Over-designing it. Keep it as plain text without text boxes, graphics or unusual symbols, which the same office warns against for applications that pass through an applicant tracking system.
Where Weydr fits
Weydr writes a cover letter for the same job you tailored your résumé to, using only facts found in your résumé. It is a draft, not a finished letter: read every line, add the example only you know, and delete anything you could not explain to an interviewer.
To check which of the posting's terms you already use before you start, paste the posting and your résumé into the free keyword checker at /resume-keyword-checker. To see how the résumé side works, see /tailor-resume-to-job-description.