The short answer
To write a letter, put your address and the date at the top, add the recipient’s name and address for a formal letter, then open with a salutation such as “Dear Ms. Rivera:” (or “Dear Sam,” for a friend). State your purpose in the first paragraph, add details in the middle, and end with what should happen next. Close with “Sincerely,” or a warmer sign-off, leave space to sign by hand, and type your name below.
What are the parts of a letter?
A formal letter is built from the same pieces in the same order every time, which is what people mean by “letter format.” Purdue OWL lists them in the order you write them: your address (unless you use letterhead), the date, the recipient’s address, the salutation, the body, the closing, your signature, and any enclosure notation. MIT’s Mayfield Handbook adds a copy notation, “cc:,” when someone else receives a copy.
A personal letter keeps only what it needs. Purdue OWL describes four basic parts: the heading, the opening, the body, and the closing. A letter to a friend may carry nothing more than the date at the top, while a complaint letter usually includes your return address and the date.
| Part | What goes in it | Formal letter | Informal letter |
|---|---|---|---|
| Heading (your address) | Street address, city, state, and ZIP Code; Purdue OWL says not to repeat your name here because it appears in the closing | Yes, unless you use letterhead | Optional |
| Date | Month written out, then day and year, such as October 9, 2026 | Yes | Usually |
| Inside address | Recipient’s name with title, job title, company, and full address | Yes | No |
| Salutation | “Dear” plus the person’s name | Yes, with a colon | Yes, with a comma |
| Body | Your message in short paragraphs | Yes | Yes |
| Closing and signature | A complimentary closing, your handwritten signature, then your typed name | Yes | Closing and signature |
| Enclosure and cc notations | “Enclosure” or “Encl.” for anything included; “cc:” for copies sent to others | Only when needed | Rarely |
What’s the difference between a formal and an informal letter?
A formal letter goes to someone you’re dealing with in an official or business capacity: a landlord, a company, an agency, an employer. An informal letter goes to someone you know personally. The difference shows up in the format, the greeting and sign-off, and the tone. Purdue OWL warns that the wrong register can undercut your message: ending a complaint letter with “Best Wishes” or “Cheers” implies a closeness you don’t intend, while opening a letter to a close friend with “Dear Ms. Mary Smithe” feels cold.
| Feature | Formal letter | Informal letter |
|---|---|---|
| Typical reader | Company, agency, landlord, official | Friend, family member, acquaintance |
| Addresses at top | Your address, date, and recipient’s address | Often just the date |
| Salutation | Dear Ms. Rivera: | Dear Sam, or Hi, Sam, |
| Punctuation after greeting | Colon | Comma |
| Tone | Concise, direct, polite | Conversational and personal |
| Paragraphs | Single-spaced, blank line between, usually not indented | Whatever reads naturally |
| Closing | Sincerely, or Yours truly, | Warm wishes that fit the occasion |
| Typed or handwritten | Usually typed and signed by hand | Often handwritten |
How do you write a letter, step by step?
These steps follow the formal order. For an informal letter, skip the inside address and loosen the tone.
- Decide what you want the reader to do or know. Write it in one sentence before you start; that sentence becomes your opening paragraph.
- Put your address at the top: street address on one line, then city, state, and ZIP Code. MIT’s Mayfield Handbook says you can use the two-letter USPS state abbreviation. Skip this if your stationery has a letterhead.
- Add the date one line below your address, with the month spelled out, such as October 9, 2026. Purdue OWL says to use the date you finished the letter if it took several days.
- Add the recipient’s address, starting one line below the date and always aligned at the left margin: title and full name, job title if relevant, company, and street address with city, state, and ZIP Code.
- Write the salutation, using the same name and title as the inside address, then leave one blank line.
- Write the body. State your purpose in the first paragraph, give the supporting details in the middle, and close with a short paragraph that says what should happen next.
- Add the closing, leave four blank lines for your signature, and type your full name below. Add your job title on the next line if you’re writing in an official capacity.
- Add end notations if needed: “Enclosure” (or “Encl. (2)” for two items) when you include documents, and “cc:” followed by each copy recipient on a separate line. MIT recommends also mentioning enclosures in the body of the letter.
- Proofread, print, and sign in ink.
How do you start a letter?
Start with a greeting that matches your relationship with the reader, then get to the point in the first paragraph.
For the first sentence of a formal letter, state why you’re writing: “I’m writing to request a refund for order 4471, which arrived damaged on September 30.” In a personal letter, open however you would in conversation.
- Dear Ms. Rivera: Standard for a formal letter. Purdue OWL says to use the person’s title and last name followed by a colon, matching the inside address.
- Dear Jordan Lee: When you don’t know which title the person uses, Purdue OWL and MIT both suggest the full name instead of guessing.
- Dear Customer Service: When you don’t know who will read it, MIT suggests naming the department and avoiding “Dear Sir or Madam.”
- Dear Lucy: If you know the person and normally use their first name, Purdue OWL says the first name alone is acceptable in a business letter.
- Dear Sam, Purdue OWL notes “Dear” works in almost any situation and doesn’t signal any particular intimacy.
- Hi, Sam, or Hello, Sam, Friendlier and less formal than “Dear,” suited to personal letters.
- Season’s Greetings, A festive opener for a holiday letter.
How do you end a letter?
End the body with a sentence that says what happens next, such as “Please reply by October 30” or “I hope to see you at Thanksgiving.” Then add a complimentary closing, capitalize only its first word, and sign underneath. Purdue OWL says to put a comma after the closing when you used a colon after the salutation; with open punctuation, you leave both bare.
| Closing | Formality | Use it for |
|---|---|---|
| Sincerely, / Sincerely yours, | Formal | Business, official, and most formal letters (MIT and Purdue OWL) |
| Yours truly, | Formal | Professional letters (MIT) |
| Regards, | Neutral, slightly distant | When you want to keep some professional distance (Purdue OWL) |
| Cordially, | Neutral | Polite letters to people you know a little (Purdue OWL) |
| Thank you, | Neutral | When you’ve asked for something (Purdue OWL’s example) |
| Best wishes, / Cheers, | Informal | Friends; avoid in complaint letters (Purdue OWL) |
| Get well soon, / Happy holidays, | Informal | Occasion-specific personal letters (Purdue OWL) |
What does a formal letter look like?
Here’s a short formal letter in block format, written by a fictional tenant to a fictional property manager. Each item is one block of the letter, top to bottom.
- Heading: 412 Maple Street, Springfield, IL 62704
- Date: October 9, 2026
- Inside address: Ms. Dana Rivera, Property Manager, Oakview Apartments, 90 Center Avenue, Springfield, IL 62701
- Salutation: Dear Ms. Rivera:
- Body, paragraph 1: I’m writing to request repair of the kitchen faucet in Unit 3B, which has leaked steadily since September 28.
- Body, paragraph 2: I reported the leak by phone on September 29 and was told a technician would visit within a week. No one has come, and water is now pooling under the sink. A photo of the damage is enclosed.
- Body, paragraph 3: Please schedule the repair by October 16. I’m available weekday mornings and can be reached at the phone number in your records.
- Closing: Sincerely,
- Signature and typed name: (signature) Alex Morgan
- Enclosure notation: Enclosure: Photo of sink cabinet
What does an informal letter look like?
An informal letter needs only the date, a greeting, the message, and a sign-off. Here’s a short example between fictional friends.
October 9, 2026
Hi, Priya,
Thanks so much for the cookbook. I made the lemon pasta on page 40 last weekend, and it’s already in heavy rotation. The new apartment is finally unpacked, and the balcony gets afternoon sun, which you’ll love when you visit in November. Let me know which weekend works and I’ll have the guest room ready.
Best wishes,
Jamie
Should you use block or modified block format?
Block format is the safe default. Purdue OWL calls it the most common layout for business letters: everything is aligned to the left margin and single-spaced, with a blank line between paragraphs. In modified block format, the addresses and body stay at the left margin, but the date and closing start at the center of the page. Semi-block is like modified block with indented paragraphs and is the least used.
Purdue OWL recommends a readable font such as Times New Roman at 12 points, though Arial is also acceptable, and reminds writers that every letter has a specific audience. If your organization or the recipient has its own letter style, MIT advises following it instead.
How do you proofread a letter before sending it?
A letter can’t be unsent, so give it one slow, deliberate read. The University of North Carolina Writing Center recommends treating proofreading as a separate last step, after you’ve finished revising what the letter says.
- Step away first. UNC suggests putting writing aside for a while so you can see what’s actually on the page.
- Don’t rely on spell checkers alone. UNC notes they miss real words used wrongly, such as “your” for “you’re” or “their” for “there.”
- Read slowly and out loud, which UNC says keeps you from skipping words or silently correcting mistakes.
- Check one kind of error at a time: spelling, then punctuation, then grammar.
- Read backward, last word first, to catch spelling errors without getting pulled into the meaning.
- Check the details that matter most in a letter: the recipient’s name and title, the date, any account or order numbers, and that every enclosure you mention is actually in the envelope.
- Print it and read the paper copy. UNC notes some people catch more on a printed page they can mark up.
How do you send a letter once it’s written?
Once the letter is signed, three steps remain: address the envelope, fold the letter, and mail it. Each has its own IRIS guide, so this article only points the way.
Write the recipient’s name and address on the front of the envelope and your return address in the upper-left corner; the envelope guide covers the exact line order, unit numbers, and abbreviations. The folding guide explains which fold fits which envelope, including tri-folds and window envelopes. The mailing guide covers choosing an envelope, placing the stamp, and where to drop the letter off.
If you typed the letter, you can skip the paper handling. Save it as a US Letter-size PDF and upload it to IRIS, an independent print-and-mail service, not USPS. IRIS prints the PDF and mails it by USPS First-Class Mail to a US address. You enter the sender and recipient addresses and review the document, addresses, options, and total before paying, with no stamps or envelope needed. A one-page black-and-white letter costs $3.20. IRIS can’t enclose physical items such as checks, photos, or original documents, so a letter with an enclosure like the photo in the formal example would need to include it as a page of the PDF or be mailed yourself.
Sources & further reading
Product details checked against the IRIS API contract when this article was published. Platform references can change; consult the linked documentation when implementing.
- Purdue OWL: Writing the basic business letter
- Purdue OWL: Personal letters
- MIT Mayfield Handbook of Technical & Scientific Writing: Letters
- UNC Writing Center: Editing and proofreading
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