Somewhere a team lead is working through a folder of applications between two meetings. She opens yours, reads two lines, and decides whether to keep reading. Almost every rule you have been told about that moment, from the perfect opening line to the keywords that supposedly beat the screening software, has never been tested.

Here is how to write a cover letter, in one sentence: say why this job, show one piece of evidence that you can do it, say what you would bring, and close by asking for the conversation. Four parts, on one page:

1. Why this job and this employer
2. Evidence you can do the work
3. What you would bring in the first months
4. A short, clear close

What hiring research actually says about cover letters

Selection researchers have spent decades measuring interviews, tests and work samples, and have barely measured cover letters at all. Paul Sackett and colleagues revisited the meta-analyses behind that literature in 2022 and found that statistical corrections used in the earlier work had overstated how accurately many hiring methods predict job performance; structured interviews ranked first.¹ Cover letters are not in that ranking, and we found no meta-analysis estimating what a letter adds.

The reason is mundane. Showing that a method predicts performance takes scores: candidates measured the same way, hired, then rated again on the job. Five interview questions, each scored 1 to 5, give you a number someone can check against the hire a year later. A letter gives prose instead, written differently by every applicant and read differently by every reader, so there is nothing to line up.

What this means for you: nobody can honestly say what a cover letter is worth, because nobody has measured it. Hold every confident claim about cover letters, including the ones here, more loosely than advice about interviews.

The one study that looked at what cover letters do

The closest thing to direct evidence comes from the International Journal of Selection and Assessment, which rated how job seekers wrote their resumes and cover letters and then followed what happened to their applications. Among 183 Canadian co-op students tracked in a 2025 study, those whose materials had more detail, clarity and structure got substantially more interviews per application, and found a position sooner.²

The study

Limited evidence

183 co-op students and the applications they sent

More detail, clarity and structure went with more interviews per application, and the link held after the researchers accounted for work experience, achievement and how far the materials were tailored.²

Nobody assigned better-written letters at random, so people who write clearly may differ in other ways that also help them get hired.

Tailoring was measured too, and how the materials were written still predicted interviews once it was accounted for.² The advice industry’s favorite instruction, rewrite everything for every job, may be doing less work than the plainer one underneath it: write the thing well.

Which applications deserve a letter at all

Write one when the letter can carry something the resume cannot: an employment gap, a career change, the name of a person who referred you, or a specific reason you want this employer. The best-designed experiment we found on cover letters tested exactly that case, with one sentence of explanation.

In 2016 Sheryll Namingit, William Blankenau and Benjamin Schwab sent 3,771 fictitious applications to 1,257 real US advertisements for sales, customer service, clerical and accounting assistant jobs. Each advertisement got three: a newly unemployed applicant, one whose cover letter explained that a long gap came from an illness followed by a full recovery, and one whose gap went unexplained. About 1 in 4 applications drew a callback: most for the newly unemployed, fewest for the unexplained gap, with the explanation recovering roughly half of the difference.³

The applicants were fictional and entry-level, and the illness was cancer, hinted at by a survivors’ group on the resume rather than named in the letter, so this is not an instruction to disclose a health condition. What it shows is narrower: employers read what a letter says about a gap.

A referral answers that question easily, and the guide to starting a job search covers what referrals do and do not do. A fourth application to the same company’s generic openings does not.

How to write a cover letter in four parts

Four short paragraphs do the work, and the order matters: the reason you are writing should reach the reader before your history does. Keep the whole thing on one page.

1. Why this job: answers: why are you writing to us, and not to everyone? Rewrite for each application
2. Evidence: answers: have you done work like this before? Keep between applications
3. What you would bring: answers: what would you actually do here first? Keep between applications
4. The close: answers: what happens next, and what do I need to know? Rewrite for each application

1. Why this job, in one specific sentence

Name the role, then one concrete thing about the work that you could not have written about a competitor: a recent product change, a service you have used, a problem the advertisement describes in unusual detail. An opening that announces you are writing to apply spends your best line on what the subject line already said.

2. Evidence you can do the work

Pick one piece of work that resembles this job and describe it in three sentences: the situation, what you did, what changed. One example told properly beats four listed in passing, and this is where the detail and structure the 2025 study measured actually live.²

3. What you would bring in the first months

Say what you would work on if they hired you. Most letters skip this, which is odd, because it is the question the reader is silently asking.

4. A short, clear close

Say you would welcome a conversation, add anything practical such as a notice period or where you are based, and stop. No summary, no thanks for their time and consideration.

1. 1Why this jobthe role, plus one thing only this employer could prompt
2. 2Evidenceone piece of work like it: what you did, what changed
3. 3What you would bringthe first months, in their terms
4. 4Closeask for the conversation, add the practical details

The letter below is invented; the shape is the point.

Run your own draft past the list below.

WiserHours

Before you send it

• The first line names the role and one specific thing about this employer
• One piece of work like this job: what I did, what changed
• A line on what I would work on in the first months
• Nothing the resume already says
• No age, date of birth, photo, marital status or health details
• Read aloud once: every sentence plain enough to say out loud
• A close that asks for a conversation and gives the practical details

Find this checklist online:
https://wiserhours.com/job-search/how-to-write-a-cover-letter/#checklist-how-to-write-a-cover-letter-draft

Write one letter you can adapt without starting over

Keep the middle and rewrite the ends. Your evidence and what you would bring change slowly; the opening line and the close change every time. That is ten minutes per job rather than an evening.

In a field experiment on an online labor market covering nearly half a million job seekers, a group whose resumes were run through writing software that corrects rather than generates text were hired about 8 percent more often than the control group, with fewer errors and easier reading in the treated resumes and no evidence that employers were less satisfied.⁴ Two of the authors were funded by that platform, and these were resumes on a freelancing site, not cover letters in a corporate hiring process, so it supports the principle rather than your letter specifically.

Plain wording is not only a matter of taste. In a 2006 lab experiment, Daniel Oppenheimer replaced every noun, verb and adjective in graduate admissions essays with its longest thesaurus synonym. The 71 Stanford undergraduates who rated them judged the complex versions more harshly whatever the quality of the original, and the effect ran through how hard the text was to read.⁵ Students judging students are not hiring managers, but the direction matches what employers mean by communication skills.

One caution applies to how you produce the letter. A 2025 preprint by Jingyi Cui and colleagues followed an online labor platform that introduced an AI cover letter tool. Access to it went with letters that matched job posts more closely and with higher callback rates, but the link between that matching and callbacks then fell by about half, and employers leaned on other signals, including work histories.⁶ That compares before and after the tool appeared rather than assigning it at random, and the preprint covers one platform and has not been through peer review.

The practical line, as of September 2026: a tool can make your letter clearer, and anything a tool can produce for everyone stops being evidence about you. No peer-reviewed study we found measures whether reviewers can identify an AI-written letter; the confident percentages come from the companies selling the tools and the detectors.

What to leave out, and what official guidance says

Leave out your age, date of birth, a photograph, marital or family status, nationality and health details. Under US federal guidance, and in England, Scotland and Wales, this is not only a matter of style: guidance as of September 2026 tells employers not to ask for most of it.

The US Equal Employment Opportunity Commission says pre-employment information should be limited to what is needed to decide whether someone is qualified, that details such as race, sex, national origin, age and religion are irrelevant to that decision, that employers are explicitly prohibited from asking about disability before an offer, and that employers should not ask for a photograph, which may be obtained for identification only after an offer has been made and accepted.⁷ In England, Scotland and Wales, section 60 of the Equality Act 2010 restricts questions about health and disability before a job offer, and Acas, Britain’s workplace advice service, states that an employer must not ask a job applicant about their health or any disability at any stage of the application or interview process unless an exception applies.⁸⁹ Acas lists exceptions, among them asking what reasonable adjustments an applicant needs for the assessment process, so asking for one is a normal part of a British application.⁸

Conventions differ, and in many countries a photograph and a date of birth are normal on a CV. Section 60 does not extend to Northern Ireland; readers there should ask the Equality Commission for Northern Ireland, and readers elsewhere their national equality body or labor ministry. Where the guidance above applies, you would be volunteering exactly what it tells employers not to ask for; it restricts their questions, not what you may choose to include. Where the answer turns on your own circumstances, an employment lawyer or the employer’s HR team can say what a guide cannot. The rest of the cutting is our own suggestion: no restatement of the resume, no account of what you hope to learn, and no apology for what you lack.

The cover letter numbers you see quoted, and where they come from

Three figures do most of the work in cover letter advice, and all three trace back to companies selling job-search or recruiting services: that recruiters spend about six seconds on a resume, that a tailored letter lifts callbacks by 53 percent over sending none, and that software rejects most applications before a person sees them.

The six-second figure comes from an eye-tracking exercise Ladders, a site selling access to high-paying job listings, ran in 2012 and updated to 7.4 seconds in 2018. Its announcement gives no sample size or job types, and the work has never been peer reviewed.¹⁰ A screening glance is also not the same as reading.

The 53 percent figure comes from a field experiment ResumeGo, a resume-writing service, ran from July 2019 to January 2020, sending 7,287 fictitious applications with no letter, a generic one or a tailored one.¹¹ The design is real, but the company selling the service published it with no method write-up and no peer review, so nothing here rests on it.

The claim about software is the loosest, though the documented part is useful. A 2021 Harvard Business School report produced with Accenture, a consulting firm whose business includes talent services, surveyed 2,275 executives in the US, the UK and Germany. More than 90 percent of those using such software said they use it to filter or rank candidates before a person looks, and nearly half said they filter out candidates whose employment gap runs more than six months.¹² That is employers describing their own settings, not a measurement of what the software does.

Myth

Packing your cover letter with keywords from the job advertisement gets you past the screening software.

Fact

Employers report setting their filters on credentials, degrees and employment gaps. We found no independent study showing that extra keywords, particular fonts or an ATS-friendly layout change the outcome.

Here is how the advice sorts by the evidence behind it, not by who is selling it.

The evidence on resumes, interviews and follow-up notes belongs to their own pages in job search, resume and interviews.

The bottom line

Cover letters are the least studied part of an application, which is why so much of the advice about them is confident and unsourced. What evidence exists points at two plain things: write clearly and in detail, and give the letter a job the resume cannot do. If it has none, keep it short and spend the time on the application itself.