The short answer
First-Class Mail is the USPS service for postcards, letters, and large envelopes (flats): letters up to 3.5 ounces and flats up to 13 ounces, with USPS listing delivery in 1–5 days. A 1-ounce letter costs $0.82 with a Forever stamp and a postcard costs $0.65, USPS retail prices effective July 12, 2026, unchanged in the October 4, 2026 Notice 123. Bills, personal letters, and handwritten or typewritten mail must go First-Class Mail or by a faster or package class, and the price includes forwarding and return when a piece can’t be delivered.
What counts as First-Class Mail?
First-Class Mail covers three shapes: postcards, letters, and large envelopes, which USPS calls flats. Each shape has its own size limits and price, and a piece that is too big or too heavy for one shape is charged as the next one up. USPS describes it as its best-priced service for items up to 13 ounces.
Packages are not First-Class Mail at retail. A flat that is rigid, not rectangular, or lumpy is charged package prices and goes by USPS Ground Advantage, and anything heavier than 13 ounces needs a package service such as USPS Ground Advantage or Priority Mail.
| Shape | Size limits | Weight limit | Starting price |
|---|---|---|---|
| Postcard | 3.5 × 5 to 4.25 × 6 inches, 0.007–0.016 inch thick | 3.5 oz | $0.65 |
| Letter | 3.5 × 5 to 6⅛ × 11½ inches, up to ¼ inch thick | 3.5 oz | $0.82 for 1 oz |
| Large envelope (flat) | Larger than a letter, up to 12 × 15 inches and ¾ inch thick; flexible and evenly thick | 13 oz | $1.69 for 1 oz |
What is an example of First-Class Mail?
Everyday examples are a birthday card, a letter to a relative, a utility bill, a bank statement, a rent check in an envelope, and a postcard. Some of these have to travel First-Class Mail. Domestic Mail Manual section 133 says the following must be mailed as First-Class Mail, USPS Ground Advantage — Retail, Priority Mail, or Priority Mail Express:
Mail that doesn’t have to go First-Class, such as advertising, can still be sent that way. USPS pitches it to businesses for its forwarding and address correction services, which help more pieces reach the intended person.
- Bills and statements of account, meaning mail that asserts a debt in a definite amount, even if it isn’t due yet.
- Mail containing personal information, which USPS defines as any information specific to the addressee.
- Handwritten or typewritten material, such as a personal letter.
- Anything marked “Postcard” or “Double Postcard”, which must go First-Class Mail, Priority Mail, or Priority Mail Express.
What is the difference between First-Class Mail and regular mail?
“Regular mail” isn’t a USPS service name. When people say it about a letter or postcard, they almost always mean First-Class Mail with a stamp and nothing added: no tracking, no signature, and no receipt beyond the postmark.
That is the real difference to weigh. Plain First-Class Mail is cheap and usually fast, but you get no record that it was sent or delivered. If you need proof, add an extra service such as Certified Mail or a Certificate of Mailing to the same First-Class letter, covered below.
What the First-Class Mail price includes
Under Domestic Mail Manual 133, First-Class Mail is sealed against postal inspection, and its price includes forwarding to a new address for up to 12 months and return to the sender if the piece can’t be delivered. That is why a returned letter costs you nothing extra.
What it doesn’t include: USPS Tracking and insurance for letters, which come only with an add-on service, and a guaranteed delivery date. If you want the postmark to show the day you mailed something, USPS says a retail associate at a Post Office counter will hand-cancel it for free.
How much does it cost for 1st class mail?
Current USPS retail prices (effective July 12, 2026, unchanged in the October 4, 2026 Notice 123): a 1-ounce stamped letter costs $0.82, each additional ounce adds $0.29 up to 3.5 ounces ($1.69), and a square, rigid, or lumpy letter adds a $0.49 nonmachinable surcharge. Postcards cost $0.65, and large envelopes start at $1.69 and reach $5.24 at 13 ounces. Businesses using a postage meter pay $0.78 for a 1-ounce letter.
Forever stamps are always valid for the current 1-ounce letter price, even after a price increase. Weight tables, stamp counts, and postcard size rules are in the two cost articles linked here.
First-Class Mail vs Priority Mail, Ground Advantage, and Marketing Mail
Those are the main types of mail USPS sells in the US. First-Class Mail is for envelopes and postcards. Priority Mail and USPS Ground Advantage are package services that include USPS Tracking and up to $100 of insurance with most shipments. When USPS Ground Advantage launched in July 2023, USPS retired First-Class Package Service, so small packages no longer go First-Class.
USPS Marketing Mail is a bulk advertising class for mailings of at least 200 pieces or 50 pounds. It can’t carry bills or handwritten or typewritten matter except under narrow exceptions, and USPS doesn’t guarantee delivery within a specified time. Every Door Direct Mail is a USPS Marketing Mail option for flats.
| Service | Use it for | USPS delivery estimate | Weight limit |
|---|---|---|---|
| First-Class Mail | Postcards, letters, and large envelopes | 1–5 days | 3.5 oz letters, 13 oz flats |
| Priority Mail | Packages and documents that need to arrive faster | 2–3 days (not guaranteed) | 70 lbs |
| Priority Mail Express | Urgent items | 1–3 days, money-back guarantee | 70 lbs |
| USPS Ground Advantage | Packages at lower cost | 2–5 days | 70 lbs |
| USPS Marketing Mail | Advertising mailings of 200+ pieces or 50+ lbs | No set time; may get deferred handling | 20 oz for presorted pieces |
How long does First-Class Mail take to deliver?
USPS lists First-Class Mail at 1–5 days, and where a letter falls in that range depends on where it starts and where it’s going. The Domestic Mail Manual is explicit that USPS doesn’t guarantee First-Class delivery within a specified time, so allow extra days for anything with a deadline. Our timing guide covers the official service standards and how to look up a specific route.
Extra services you can add to First-Class Mail
First-Class Mail is eligible for the extra services that create a record. The fees below are paid on top of postage, at USPS retail prices effective July 12, 2026, unchanged in the October 4, 2026 Notice 123. Return Receipt is only available together with another extra service, such as Certified Mail.
| Extra service | What you get | Fee |
|---|---|---|
| Certified Mail | A mailing receipt and electronic verification of delivery or a delivery attempt | $5.55 |
| Certified Mail Restricted Delivery | Delivery only to the named addressee or the addressee’s authorized agent | $14.35 |
| Return Receipt | A delivery record with the recipient’s signature, by email (electronic) or on a green card (hardcopy) | $2.91 electronic, $4.65 hardcopy |
| Certificate of Mailing (PS Form 3817) | Evidence that the piece was presented for mailing; no delivery record | $2.45 |
| Registered Mail | USPS’s most secure service, with receipts tracking the piece from acceptance to delivery | From $20.90 |
How IRIS uses First-Class Mail
IRIS prints individual letters from an uploaded US Letter-size PDF, and postcards, and mails them to US addresses by USPS First-Class Mail. A one-page black-and-white letter costs $3.20 in total: a $3.00 service-and-postage fee plus $0.20 per black-and-white page or $0.40 per color page. Certified Mail adds $6.95, and an electronic Return Receipt adds $2.91 with Certified Mail. Postcards cost $3.49 or $4.49 with printing and First-Class postage included.
IRIS doesn’t sell stamps, ship packages, mail large envelopes, or send mail internationally, and it doesn’t offer Priority Mail, Registered Mail, Restricted Delivery, the hardcopy Return Receipt, or the retail PS Form 3817 Certificate of Mailing. It doesn’t guarantee a delivery date either: like any First-Class letter, timing depends on USPS.
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.
- USPS, First-Class Mail
- USPS, Mail & Shipping Services (compare mail services)
- USPS Domestic Mail Manual 133, First-Class Mail and USPS Ground Advantage — Retail prices and eligibility
- USPS Domestic Mail Manual 101, Physical Standards
- USPS Notice 123, Price List (Postal Explorer)
- USPS newsroom, U.S. Postal Service Recommends New Prices for July (April 9, 2026)
- USPS newsroom, Introducing USPS Ground Advantage (July 10, 2023)
- USPS, Priority Mail
- USPS, USPS Ground Advantage
- USPS Domestic Mail Manual 243, USPS Marketing Mail prices and eligibility
- USPS Domestic Mail Manual 503, Extra Services
Published by IRIS Postal Forms, operated by Great Lakes Computing Office LLC. Send a correction.