How many stamps for a postcard?

Q: Do international postcards cost more?

Yes. Domestic postcard pricing does not apply worldwide. For many international postcards you use a Global Forever stamp (or the correct international postage for your destination and service).

Q: Is a 5×7 card still a postcard?

Not at the postcard rate. Anything larger than 4.25 inches by 6 inches (within thickness limits) is not a USPS postcard—it mails as a letter. At 1 oz that is typically $0.78 with a letter Forever stamp, not $0.61.

Q: How many postcard stamps for one standard postcard?

One postcard-rate stamp covers the flat $0.61 retail postcard price for a qualifying piece at 1 billable ounce—there is no additional-ounce ladder for postcard rate like letters.

How many stamps do I need for a postcard in 2026?

In 2026, a qualifying USPS postcard mails at a flat $0.61 retail rate—typically one postcard stamp (or Postcard Forever at the postcard rate). If the card is larger than postcard limits (for example a 5″ × 7″ piece), USPS prices it as a letter—often $0.78 for 1 oz with a letter Forever stamp. Use the calculator with your exact length, height, and thickness.

A standard USPS postcard mails at a flat retail rate—no letter “additional ounce” ladder. Enter your measurements below; if you stay within postcard limits at 1 billable ounce, you need one postcard-rate stamp.

Mail class

Auto (from dimensions & weight)LetterLarge envelope / Flat

Weight (oz)

Length (in)

Height (in)

Thickness (in)

Shape & contents

Square envelope (height and length similar)Rigid (cards, stiff mailers)Contains objects (not paper only)

Classification

USPS postcard (retail postcard size)

Total postage

$0.61

Postcard rate$0.61
Additional ounces (letter ladder; not used on postcard rate)$0.00
Non-machinable surcharge$0.00

Stamps to use

Use 1 postcard stamp ($0.61) or a Postcard Forever stamp at the postcard rate—not letter Forever math.

Notes

Weight rounded up to 1 oz.

Piece qualifies as USPS postcard size at 1 billable oz.

Postcard rate is a flat retail price (no letter additional-ounce ladder).

Rates updated: March 2026 — Based on USPS First-Class Mail retail pricing

Postcard rate applies to USPS-defined postcard size at retail; oversized pieces use letter rates.

Stamps at a glance (standard letter)

Rounded to whole ounces; totals use current First-Class letter rates in this calculator.

1 oz → 1 stamp (1 Forever stamp) — $0.78 total
2 oz → 2 stamps (1 Forever + 1 additional ounce) — $1.07 total
3 oz → 3 stamps (1 Forever + 2 additional ounce) — $1.36 total
Non-machinable (square, rigid, or lumpy) → + $0.49 surcharge on top of the ounce total

The postcard size rule (USPS)

Postcard postage is only for pieces that fit all of these retail size windows at once (length and height can be swapped):

Minimum: 3.5″ × 5″ and at least 0.007″ thick
Maximum: 4.25″ × 6″ and no more than 0.016″ thick

The shortest side must fall between 3.5″ and 4.25″, and the longest side between 5″ and 6″, with thickness between 0.007″ and 0.016″. Anything larger—like a common 5″ × 7″ souvenir card—does not qualify for the postcard rate; it is processed as First-Class letter mail, usually $0.78 for 1 oz with a letter Forever stamp, not $0.61.

Postcards use a flat retail rate ($0.61)—not the letter ladder where each additional ounce adds $0.29. Once your piece is too big for postcard dimensions, letter rules (and that ladder) apply.

Postcards are a size class, not “light letters”

The postcard retail rate only applies when length, height, and thickness fit USPS postcard windows. Oversized cards mail as letters—this page separates those paths so you do not use letter Forever pricing when a cheaper postcard stamp would work.

When the postcard rate applies

Use the preset below when you have a thin, stiff card within maximum postcard dimensions—tourist postcards, small notices, or reply pieces that truly meet the size rule. Anything larger (for example a typical 5″ × 7″ photo card) is priced as a letter at 1 oz or more, not at the postcard stamp.

Common postcard mistakes

Using a postcard stamp on a 5×7 — oversized cards need letter postage; measure before you buy.
Ignoring thickness — too thick fails postcard class even when length and width look fine.
Assuming Forever always saves money — on a true postcard, letter Forever covers postage but overpays versus a postcard rate stamp.

Postcard rate vs letter rate in 2026

For 2026 USPS retail pricing, a standard postcard stamp matches the postcard class: $0.61 flat for a qualifying piece. The letter First-Class rate for the first ounce is $0.78—that is what a typical Forever stamp sold for letters is designed to cover. If you put a letter Forever on a true postcard, the postage is valid, but you pay about $0.17 more than necessary compared with a postcard-rate stamp.

Mailing a folded letter in an envelope instead? Use 1 oz letter postage when you are at the first-ounce letter step—not this postcard flow.

Why the calculator asks for size, not just weight

Weight alone cannot tell you whether you are at the $0.61 postcard rate or the $0.78 letter rate. The same ounce count on a 4″ × 6″ card can qualify as a postcard, while a 5″ × 7″ card at the same weight is priced as a letter. Enter length, height, and thickness so the tool can apply the postcard size rule before stamp math.

International and specialty mail

This page focuses on domestic U.S. postcard sizing and retail rates. International postcards use different products and prices—often a Global Forever stamp for simple international letter/postcard mail—and customs rules may apply. When in doubt, use USPS’s international postage tools or ask at the counter.

Frequently asked questions

Can I use a Forever Stamp on a postcard?

Yes. A letter Forever stamp covers the First-Class letter rate ($0.78 in 2026), which is more than the postcard rate ($0.61). You overpay by about $0.17 versus a postcard stamp or Postcard Forever at the postcard rate.

Do international postcards cost more?

Yes. Domestic postcard retail pricing does not apply worldwide. For many international postcards you use a Global Forever stamp (or the correct international postage for your destination and mail class—check USPS international options).

Is a 5×7 card still a postcard?

Not at the postcard rate. A typical 5″ × 7″ souvenir or photo card exceeds the maximum postcard dimensions, so USPS treats it as a letter. At 1 billable ounce that is usually $0.78 with a letter Forever stamp—not $0.61.

How many postcard stamps for one standard postcard?

For a piece that meets USPS postcard size at 1 billable ounce, you need one postcard-rate stamp ($0.61 total). The postcard rate does not add letter “additional ounce” steps—that logic applies once the mail is priced as a letter.

Educational estimate only. Not affiliated with USPS. Confirm size, class, and retail products at the post office or on USPS.com.