By ShowMeStepByStepPublished Updated
Based on a video by Innominate Kraken.
USPS First-Class Mail covers everything most people send: greeting cards, paper checks, paperwork, anything that fits in a standard envelope under 3.5 ounces. The video walks through which stamps you actually need for which letter type, and what to do when the standard rules don't fit (square envelope, heavier than 1 oz, going overseas).
The everyday case: drop a Forever stamp on a standard envelope, drop it in a USPS blue collection box. Done in 30 seconds. Everything below covers the variations on that.
Heavier letters (over 1 ounce). A Forever stamp covers up to 1 oz. Each additional ounce needs an "additional ounce" stamp (a smaller-denomination stamp the USPS sells alongside Forever stamps). Two-stamp letters are common for thick greeting cards, multi-page checks, or anything mailed in a padded envelope.
Square envelopes (wedding invitations, fancy cards). Need extra postage regardless of weight because they're "non-machinable" — the auto-sort can't process square shapes, so a human has to hand-sort them. As of 2026 the surcharge is about $0.40 over a standard Forever stamp.
International mail. Use a "Global Forever" stamp (one stamp, any country, up to 1 oz). Don't put a regular Forever stamp on international mail; it'll either be returned to you or charged to the recipient on arrival. For packages, use the USPS Postage Price Calculator — international rates depend on country, weight, and customs declarations.
Certified, registered, or tracking. Anything that needs proof of delivery (legal documents, tax returns, contracts) goes to a post office counter, not a blue box. The clerk adds a tracking barcode and you get a receipt with a number you can monitor online.
Semi-postal stamps (cause donations). The USPS sells stamps where a small portion of the price funds a specific cause (breast cancer research, Alzheimer's research, military families). They work as first-class postage and the extra cents go to the program. Same usage as Forever stamps with a built-in donation.
One Forever stamp (current value ~$0.73 as of 2026) covers a standard envelope up to 1 ounce going anywhere in the U.S. Each additional ounce is about $0.28. International mail is one Global Forever stamp (~$1.65) for letters up to 1 oz. The stamps cost more if you buy them individually at a post office than at a grocery store or online from USPS.com.
Yes, but USPS recommends including one. Without a return address, if the recipient's address is wrong or they've moved, the letter goes to the USPS Mail Recovery Center in Atlanta — also called the "dead letter office" — and gets opened to find a return clue. Anything with a return address comes straight back to you instead.
Use the USPS Service Locator at tools.usps.com/find-location.htm — filter by "Collection Box" and enter your zip. They're outside most post offices, in front of many grocery stores, and on busier residential corners. The blue boxes have a pickup schedule sticker on the side; drop your letter before the last-pickup time and it ships the same day.
USPS targets 2-5 business days for first-class within the U.S. Local mail (same metro area) often arrives next day; cross-country mail takes 3-5 days. International varies wildly: 6-10 business days to Canada and Mexico, 10-20 to Europe and Asia, longer for remote countries. There's no guarantee or refund if delivery runs slow.
Drop the letter at the post office counter and pay the clerk in cash or card. They print a postage label on the spot. If you have no time, many grocery stores, drugstores, and gas stations sell Forever stamps; some self-service postal kiosks at larger post offices accept payment for stamps 24/7 even when the counter is closed.
First-Class is the standard USPS service for letters. You get 1-3 business day delivery, loss/damage insurance up to $5,000 for merchandise, and eligibility for Certified Mail tracking add-ons. It's what most people mean when they say 'send a letter.'
Tip
If you want tracking on a First-Class letter, you have to pay extra for Certified Mail at the post office counter. Stamps alone don't include tracking.
Standard letter envelopes max out at 3.5 ounces. Anything bigger - like a manila envelope, a padded envelope, or a 9x12 flat - is classified as a 'large envelope' (also called a flat) which can hold up to 13 oz at a higher rate.
If your envelope is too thick to fit through a postal sorting machine (~1/4 inch thick), it's automatically classified as a package and priced higher.
Forever stamps are always valid at the current First-Class rate, even years after you bought them. One Forever stamp covers a standard envelope under 1 ounce - the most common case for greeting cards, single-sheet letters, and bills.
Tip
Forever stamps are a small inflation hedge. If postage rises next year, the ones you bought this year are still valid at the new rate.
Each ounce above the first costs about 20 cents extra. USPS sells additional-ounce stamps specifically valued at this rate, or you can stack a Forever stamp with smaller-denomination partial stamps. Two-ounce and three-ounce stamps (75 cents and 95 cents) also exist for common heavier letters.
Semi-postal stamps are valid for First-Class postage and direct extra cents to charity. The two current ones support PTSD treatment and breast cancer research. They're priced slightly higher than the regular rate (currently 65 cents) so you'd combine with partial stamps to hit the rate you need.
For non-standard letters - heavy ones, large envelopes, anything you're not sure about - go to postcalc.usps.com. Enter both ZIP codes and the weight, pick whether it's a Letter, Large Envelope, Package, or Large Package, and it tells you the exact retail postage required.
Tip
If the calculator gives you a price like $0.78, you can use one Forever stamp (currently 73 cents) plus a 5-cent partial stamp - or just round up to two Forever stamps. The post office accepts overpayment.
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