Cheapest Way to Post a Letter in 2026: USPS Rates Guide

Sending a letter shouldn’t be complicated or expensive. The cheapest way to post a letter is by using USPS First-Class Mail to send a standard-sized postcard or a one-ounce letter. Whether you’re mailing a single greeting card or hundreds of business invoices, finding the most affordable method is all about understanding a few simple rules from the U.S. Postal Service. This guide breaks down everything you need to know, from standard stamps to surprise surcharges, helping you keep your mailing costs as low as possible. If you’re brand new to mailing, start with this step-by-step how to mail a letter checklist.

The Go To Service for Cheap Letter Mailing: USPS First Class Mail

For everyday letters, postcards, and large envelopes (also known as flats), USPS First Class Mail is your best bet. It’s the standard, most affordable mail service available. It offers a great balance of low cost and reliable speed, with most letters arriving anywhere in the country within about 1 to 5 business days. Around federal holidays, delivery can slow. Check the USPS holidays calendar before you send.

One of the best perks of First Class Mail is that it includes free forwarding if your recipient has moved and filed a change of address. If the letter is undeliverable for any reason, it will be returned to you at no extra charge. This makes First Class Mail the undisputed cheapest way to post a letter for most everyday needs.

The Two Cheapest Options at a Glance

Postcards: If your message is short and not confidential, sending it as a postcard is an incredibly cheap option, costing less than a standard letter stamp.
Standard Letters (1 oz): For a standard letter weighing one ounce or less, a single Forever Stamp is all you need. The beauty of a Forever Stamp is that its value is always equal to the current first class one ounce letter rate, no matter when you bought it. Need to pick some up? Here’s where to buy stamps for the best price and convenience. A stamp purchased for 60 cents in 2022 is still valid when the rate is 68 cents. This makes them inflation proof. If you buy in bulk, see how much is a book of stamps so you know what to budget.

Understanding What Affects Your Postage Cost

The cheapest way to post a letter involves sending a standard, one ounce piece of mail. Costs begin to climb when your letter is heavier, larger, or has an unusual shape.

Heavier Letters and the Additional Ounce Price

A standard stamp covers the first ounce of your letter’s weight. If it weighs more, you need to add extra postage.

Weight Limit: The maximum weight for a letter to qualify for letter rates is 3.5 ounces.
Additional Ounce Cost: Each extra ounce (or fraction of an ounce) costs an additional $0.24. For example, a 2 ounce letter would require postage for the first ounce plus an additional 24 cents for the second ounce. To see current prices across services, use the USPS rates calculator and chart.
Over 3.5 Ounces: Once your mailpiece exceeds 3.5 ounces, it no longer qualifies for letter rates and will be priced at the higher rate for a large envelope or flat.

Bigger Mail: When a Letter Becomes a “Large Envelope”

If your envelope is larger than the standard dimensions, USPS classifies it as a large envelope or flat. This immediately increases the base postage price.

Size Threshold: An envelope becomes a flat if it exceeds any of these dimensions: 6⅛ inches in height, 11½ inches in length, or ¼ inch in thickness.
Higher Starting Price: The postage for a one ounce flat is significantly more than a one ounce letter (for example, $1.26 vs $0.63 in a past rate schedule).
Flexibility is Key: A flat must be flexible. If it’s rigid, USPS will charge you a much more expensive parcel rate. Simply folding your document to fit into a standard letter envelope can cut your postage cost in half.

How to Avoid Surprise Fees and Surcharges

Finding the cheapest way to post a letter often means avoiding extra fees. The most common is the nonmachinable surcharge, an extra fee applied to letters that cannot be processed by automated sorting machines.

The Nonmachinable Surcharge Explained

If your letter requires manual handling, USPS adds a surcharge (currently $0.40) on top of the regular postage. Here’s how to avoid it:

Use Rectangular Envelopes: Square envelopes are a primary trigger for this fee. A 5x5 inch invitation, for example, is nonmachinable. The length of a letter divided by its height must be between 1.3 and 2.5 to be machine friendly. To save money, place your square card inside a standard rectangular envelope.
Keep it Flexible: Your letter must be able to bend. Envelopes containing rigid items like keys, coins, or stiff cardboard will incur the surcharge. A rigid mailpiece within letter dimensions costs extra, but a rigid large envelope gets bumped up to the much higher parcel price.
Avoid Lumps and Bumps: Uneven thickness from items like pens or clasps can also make a letter nonmachinable. Opt for plain, self sealing envelopes.
Correct Address Orientation: Always write the address parallel to the longest side of the envelope. For format, follow these steps on how to address an envelope; a “tall” or vertical address orientation will trigger the surcharge.

More Pro Tips for the Cheapest Way to Post a Letter

Beyond avoiding fees, you can take a few more steps to lower your mailing costs.

Print Postage Online: Using an approved online service or a postage meter gets you a small discount on every letter you send. The “Metered Mail” rate is typically a few cents cheaper per letter than the price of a physical stamp. This might not seem like much, but the savings add up for businesses that mail frequently. If you just need stamps, you can also buy stamps online and skip the post office trip.
Skip Optional Services: USPS offers add ons like Certified Mail, Return Receipt, and insurance. These provide peace of mind but dramatically increase your cost. A Certified Mail service can add over $4.00 to your postage. If you don’t absolutely need proof of delivery, skipping these extras is a core part of finding the cheapest way to post a letter.
Calculate the Exact Postage: Don’t guess and overpay by adding extra stamps “just in case.” Use an online tool to find the precise cost. The official USPS Price Calculator is a reliable resource. For an easy to use interface that helps you visualize your costs, you might try using an online postage calculator like the one found at OnlineShippingCalculator.com.

By following these guidelines, you can ensure you are always using the cheapest way to post a letter, saving you money on every piece of mail you send.

Frequently Asked Questions

What is the absolute cheapest way to post a letter?

The cheapest way to post a letter is to send a standard size, rectangular postcard using USPS First Class Mail, as it costs less than a one ounce letter. For confidential mail, the cheapest method is a standard rectangular letter weighing one ounce or less, sent with a single Forever Stamp.

How many stamps do I need for a 2 ounce letter?

A 2 ounce letter requires postage to cover the first ounce (one Forever Stamp) plus the charge for one additional ounce ($0.24). You would need the total postage value, not necessarily two stamps. Using a postage calculator is the best way to be sure; for a quick walkthrough, here’s how to calculate shipping costs step by step.

Does a square greeting card really cost more to mail?

Yes. Square envelopes are considered “nonmachinable” by USPS because their shape doesn’t work with automated sorting equipment. This means you must pay a nonmachinable surcharge (currently $0.40) in addition to the base postage. To avoid this, place your square card inside a standard rectangular envelope.

How can I save money if I mail a lot of letters?

If you send mail frequently, the cheapest way to post a letter is to use an online postage service or a postage meter. This gives you access to the discounted “Metered Mail” rate, which saves you a few cents on every First Class letter compared to the price of a stamp.

What happens if I put too little postage on a letter?

If you underpay postage, USPS will typically return the letter to you with a notice indicating the amount of postage due. This delays your mailing, so it’s always best to calculate the correct postage before sending. You can easily find the right amount with a tool like the online shipping calculator.

Is a Forever Stamp always the cheapest way to post a letter?

A Forever Stamp is the standard price for a one ounce letter. The cheapest way to post a letter is to use the discounted “Metered Mail” rate by printing your own postage online, which is a few cents cheaper per letter than a Forever Stamp.

When should I use a large envelope (flat) instead of a letter?

You must use a large envelope if your mailpiece exceeds the maximum dimensions for a letter (11½″ long, 6⅛″ high, or ¼″ thick) or if you are mailing documents you cannot fold. Remember that postage for flats starts at a higher price.