First class mail covers more than letters and postcards. Small packages under 13 ounces qualify too, which surprises plenty of people used to thinking of it purely as stamp mail.
It is the default class for most everyday mail in the United States. It is also the one every Forever stamp actually pays for.
Here is exactly what first class mail covers and what it costs. This also covers how it compares to the other USPS classes.
What first class mail actually covers
Letters, postcards, and large envelopes all ship as First-Class Mail up to 3.5 ounces. Small packages qualify too, as long as they stay under 13 ounces total.
Anything heavier needs a different class entirely, typically USPS Ground Advantage or Priority Mail. Our guide to USPS Ground Advantage covers that next tier up.
How much First-Class Mail costs
A standard 1 ounce letter costs 82 cents using a Forever stamp. Postcards cost 65 cents. Each additional ounce on a letter adds 29 cents on top of the base rate.
Small packages under 13 ounces are priced by weight rather than a flat stamp rate. That pricing usually starts a few dollars above the letter rate. Our current stamp pricing guide covers every letter and postcard rate in detail.
How long First-Class Mail takes
USPS publishes a 1 to 5 business day delivery window for First-Class Mail. Nearby addresses typically land at the faster end, and cross country mail lands closer to the slower end.
That window held steady through the 2025 service standard changes. USPS did shift more mail from air to ground transport during that update for cost reasons. Some longer routes now run closer to the upper end of that window than they used to.
First class mail versus Priority Mail
Priority Mail moves faster, typically 2 to 3 days. It also covers packages up to 70 pounds instead of 13 ounces, and it costs more, starting at $11.00 versus a fraction of that for a first class letter.
Choose first class mail for anything light enough to qualify, since it is almost always the cheaper option. Our full guide to Priority Mail covers when the faster, heavier option actually makes sense. Our guide to Media Mail covers an even cheaper option for eligible books and media.
Tracking First-Class Mail
Standard first class letters do not include tracking by default. Only a delivery confirmation if certified mail or another add on service is attached shows up. First-Class packages under 13 ounces do get a tracking number automatically.
That distinction confuses a lot of senders expecting to track a plain letter the way they would a package. A letter mailed with just a stamp genuinely has no tracking number to look up.
What happens if a First-Class item is too heavy
USPS will typically still deliver a slightly overweight first class piece if it was accepted at the counter with correct postage for its actual weight. A piece that exceeds 13 ounces needs to ship as Ground Advantage or Priority Mail instead.
Self service kiosks and online postage tools calculate weight automatically. That helps avoid an underpaid piece getting flagged or returned. Weighing an item before applying postage is always worth the extra minute, and our stamp calculator can confirm exact postage for a specific letter before you seal the envelope.
Frequently asked questions
What is First-Class Mail?
It is the standard USPS class for letters, postcards, and small packages up to 13 ounces. It is the class every Forever stamp pays for.
How long does First-Class Mail take?
USPS publishes 1 to 5 business days as the standard delivery window. Nearby addresses tend toward the faster end, and cross country mail toward the slower end.
Does First-Class Mail include tracking?
Only for packages, not standard letters. A First-Class package under 13 ounces gets a tracking number automatically, while a plain stamped letter does not.
What is the weight limit for First-Class Mail?
13 ounces for packages. Letters and large envelopes have their own separate ounce based pricing tiers below that ceiling.
Is First-Class Mail cheaper than Priority Mail?
Yes, significantly, for anything light enough to qualify. First-Class Mail starts at stamp pricing, while Priority Mail starts at $11.00.
Can I ship a small package with a Forever stamp?
Only if it weighs 3.5 ounces or less and meets letter shaped requirements. Anything heavier or oddly shaped needs package postage instead of a stamp.
The bottom line
First class mail covers the everyday basics: letters, postcards, and small packages under 13 ounces, all at the lowest USPS price point. It trades speed and weight capacity for that lower cost.
Once an item exceeds 13 ounces, USPS Ground Advantage or Priority Mail takes over. See our full comparison of every USPS mail class to figure out which one fits your specific mailing.