USPS Postage Calculator

Marko ŠinkoCo-Founder & Lead Developer

November 21, 2025•Shipping & Freight

How Much Does a Postage Stamp Cost in 2026? Complete USPS Rate Guide

Wondering how much does a postage stamp cost right now? As of January 2026, a Forever Stamp costs $0.78— that covers one ounce of domestic First-Class mail. But depending on what you are sending, you might need more than one stamp, a different type of stamp entirely, or a completely different mail class. Whether you are mailing a birthday card, a stack of wedding invitations, a 9x12 envelope stuffed with documents, or a flat-rate care package across the country, knowing the correct postage saves you from the frustration of returned mail or a "Postage Due" notice landing in your recipient's mailbox.

Our USPS Postage Calculator tells you exactly how much it costs to mail a letter at any weight: enter your mail type, weight (or number of pages), and we show you the exact cost and how many stamps you need. We keep our rates aligned with the most recent USPS price changes so you can plan your mailing with confidence. In this guide, we walk you through how to use the calculator, explain every mail class, share money-saving tips, and answer the most common postage questions we see from our readers.

How to Use Our USPS Postage Calculator

Using our tool takes less than 30 seconds. Here is a step-by-step breakdown so you get the most accurate estimate every time. If you are specifically looking for package shipping rates rather than letter postage, our USPS Shipping Calculator is more specialized for that purpose.

1. Select Mail Type: Choose the category that best fits your item.
   • Standard Letter: Regular envelopes (No. 10, 6x9) used for bills, greeting cards, or personal letters.
   • Postcard: Rectangular cards without envelopes (minimum 3.5" x 5", maximum 4.25" x 6").
   • Large Envelope (Flat): 9x12, 10x13, or similar manilla envelopes for documents — flexible and uniformly thick.
   • Priority Mail Flat Rate: USPS-branded boxes and envelopes that ship for a fixed price regardless of weight.
2. Enter Weight (or Use the Pages Estimator): For letters and flats, weight is the primary cost factor. A standard sheet of paper plus a No. 10 envelope weighs about 1 ounce. If you don't have a scale, use our built-in pages-to-weight estimator — just enter the number of pages and envelope type, and we calculate the weight for you automatically.
3. Set Quantity: Mailing invitations, holiday cards, or bulk letters? Enter the number of identical items you need to send, and we will calculate both the per-item and total postage cost.
4. Toggle Non-Machinable (if applicable): Square envelopes, rigid cards, or lumpy letters require a surcharge because they cannot pass through automated USPS sorting machines. Our calculator adds the surcharge automatically when you enable this option.
5. Select Destination:Toggle between "Domestic (USA)" and "International" to see the difference. International letters use the Global Forever Stamp rate.
6. Calculate: Hit the button to see your cost, a description of the postage you need, and the number of Forever Stamps required.

How Much Does a Postage Stamp Cost in 2026?

This is one of the most common questions we get, and the answer changes regularly because USPS adjusts rates — typically in January and July of each year. As of the January 2026 rate adjustment, here are the current USPS postage prices:

*Rates are set by the Postal Regulatory Commission (PRC). Always verify the latest pricing on the official USPS website or the Postal Explorer.

How Many Stamps Do I Need? (By Weight)

This is the second most-searched question related to USPS postage. The answer depends on the weight of your letter or envelope and whether it qualifies as a standard letter or a large envelope (flat). Here is a quick reference for domestic First-Class letters:

• 1 oz or less (1-4 sheets of paper + envelope): 1 Forever Stamp — $0.78
• 2 oz (~8-10 sheets + envelope): 1 Forever Stamp + 1 Additional Ounce stamp — $1.06
• 3 oz (~14-15 sheets + envelope): 1 Forever Stamp + 2 Additional Ounce stamps — $1.34
• 3.5 oz (maximum for a standard letter): 1 Forever Stamp + 3 Additional Ounce stamps — $1.62

If your letter weighs more than 3.5 oz, USPS automatically classifies it as a Large Envelope (Flat), which starts at $1.50 for the first ounce. You can use 2 Forever Stamps for any weight up to 3.5 oz if you don't have Additional Ounce stamps, though you'll overpay slightly. For a more precise calculation, enter the weight into our calculator above and we will tell you exactly what you owe.

How Much Does It Cost to Mail a Letter in 2026?

The cost to mail a standard letter depends on its weight and shape. For a typical domestic letter weighing 1 ounce or less — think a greeting card, a bill payment, or a single-page letter in a #10 envelope — you need one Forever Stamp ($0.78). That is the most common mailing scenario and the simplest answer to "how much postage do I need."

If your letter is heavier, each additional ounce up to 3.5 oz costs an extra $0.28. So a 2-ounce letter (about 8-10 pages of paper in a standard envelope) costs $1.06 total. Once your letter exceeds 3.5 ounces, USPS reclassifies it as a Large Envelope (Flat) at $1.50 for the first ounce — a significant jump. This is why weighing your mail matters: the difference between 3.5 oz and 4 oz is the difference between $1.62 and $1.78, plus you lose the ability to use standard Forever Stamps efficiently.

For international mail, a single Global Forever Stamp at $1.65 covers letters up to 1 oz to any country. Beyond that, international rates are zone-based and vary significantly — we recommend checking postcalc.usps.com for exact international pricing on heavier items.

Understanding USPS Mail Classes

USPS offers several classes of mail, each with its own pricing structure and rules. Picking the right class helps you avoid overpaying and ensures your mail meets size and weight requirements.

First-Class Mail: Letters and Postcards

First-Class Mail is the most commonly used service for personal correspondence — everything from greeting cards and bills to thank-you notes and invitations. Standard letters (No. 10 envelopes) must be rectangular, flexible, and at most 3.5 ounces. A single Forever Stamp covers the first ounce, and each additional ounce costs $0.28. Postcards must measure at least 3.5" x 5" but no larger than 4.25" x 6" to qualify for the lower postcard rate.

Large Envelopes and Flats (6x9, 9x12, 10x13)

"Flats" is the USPS term for large envelopes like the 9x12 or 10x13 manilla envelopes commonly used to send documents without folding them. A 6x9 envelope can sometimes qualify as a standard letter if it is flexible and within weight limits, but 9x12 and larger always count as Flats. To qualify for the Flat rate, your envelope must be flexible (bendable), uniformly thick (no bumps), and rectangular. The first ounce costs $1.50, each additional ounce adds $0.28, and the maximum weight is 13 ounces. If your large envelope is rigid or exceeds 3/4-inch thickness, USPS reclassifies it as a "Package," which costs significantly more.

How Much Postage for a 6x9 Envelope?

A 6x9 envelope is a borderline size that can qualify as either a standard letter or a large envelope, depending on its contents. If your 6x9 envelope is flexible, uniformly thick (less than 1/4 inch), and weighs 3.5 oz or less, USPS treats it as a standard letter— meaning you pay the regular letter rate starting at $0.78 for 1 oz. However, if the contents make it rigid, lumpy, or heavier than 3.5 oz, it gets reclassified as a Flat at $1.50+ per ounce. Our calculator handles both scenarios: select "Standard Letter" for flexible 6x9 envelopes or "Large Envelope (Flat)" if the contents are rigid or heavy.

How Much Postage for a 9x12 or 10x13 Envelope?

A 9x12 envelope (or 10x13) always qualifies as a Large Envelope (Flat) under USPS rules. The postage starts at $1.50 for the first ounce and $0.28 for each additional ounce, up to a maximum of 13 oz. For example, a 9x12 envelope with 10 pages of paper and the envelope itself weighs roughly 2.4 oz, costing $2.06. If your large envelope exceeds 13 oz or is more than 3/4-inch thick, USPS reclassifies it as a package — dramatically increasing the cost. If you frequently mail 9x12 envelopes, our General Postage Calculator also provides quick comparisons across multiple mail classes.

Priority Mail Flat Rate

For heavier items (up to 70 lbs), Priority Mail Flat Rate is often the best deal. You use free boxes and envelopes provided by USPS (order them at usps.com or pick them up at your local post office), and the price is the same regardless of weight or destination within the US. If you are comparing USPS with other carriers, try our UPS Shipping Calculator to see which service offers the best rate for your package.

• Flat Rate Envelope ($10.10): Perfect for heavy documents, contracts, or small items that fit in the envelope.
• Small Flat Rate Box ($10.65): Ideal for jewelry, electronics, or small dense items.
• Medium Flat Rate Box ($18.80): Good for shoes, clothing, and mid-size care packages.
• Large Flat Rate Box ($25.20): For larger gifts, multiple books, or bulky items.

Tips for Saving Money on USPS Postage

Shipping costs add up, especially if you send mail regularly. Here are practical ways to keep costs down:

1. Buy Forever Stamps Before Rate Increases: Forever Stamps retain their value indefinitely. If a rate hike is announced (USPS usually announces changes 45 days in advance), stock up at the current lower price. They will still cover one ounce of First-Class postage even after the price goes up.
2. Use a Kitchen Scale:Guessing weight leads to over-stamping "just to be safe." A simple kitchen scale can save you from wasting an extra Forever Stamp when a $0.28 Additional Ounce stamp would be enough.
3. Fold to Save: If you are mailing a few pages in a large 9x12 envelope, consider folding them into a standard No. 10 envelope instead. You will drop from the $1.50 Flat rate down to $0.78 — saving over 50%.
4. Avoid the "Non-Machinable" Trap: Square cards, rigid envelopes, and letters with lumpy contents (keys, USB drives, gift cards) all trigger a $0.46 surcharge. Use standard rectangular envelopes and padded mailers when possible.
5. Ship Online for Packages:USPS offers discounted "Commercial Base" pricing when you print labels through their online portal or third-party services like PirateShip or Stamps.com.

Common Postage Mistakes to Avoid

• The "Square" Trap: Square greeting cards look elegant but require extra postage (non-machinable surcharge of $0.46) because they jam automated sorting machines. This catches many people off guard around the holidays.
• The "Lumpy" Letter: Inserting a gift card, key, or USB drive into a standard letter makes it uneven and non-machinable. You will need the surcharge or potentially package rates.
• Oversized "Letters": An envelope that is even slightly over 6-1/8 inches tall or 11-1/2 inches long gets reclassified as a Flat, nearly doubling the postage cost.
• Stamp Placement: Always place stamps in the top-right corner. Stamps placed elsewhere can delay automated processing and potentially cause delivery issues.

USPS Postage Calculator vs. USPS.com PostCalc

The official USPS Postage Price Calculator (postcalc.usps.com) is thorough but can be slow and overwhelming with options. Our calculator is designed for the most common use case: quickly finding out how much it costs to mail a letter, postcard, or flat envelope. We show you the cost, the specific stamps you need, and the number of Forever Stamps required — all in one clean result. For less common scenarios (Media Mail, USPS Ground Advantage zone-based pricing, or international packages), we recommend checking postcalc.usps.com directly. You can also explore our General Postage Calculator for a broader comparison across different mail types.