How wedding invitation postage works
Invitation postage is decided by three things, in this order: what kind of mail the envelope counts as, how much it weighs, and whether a machine can sort it. The calculator above checks all three the way a postal clerk would and shows the rule behind each answer.
Prices come straight from the USPS price list that took effect on October 4, 2026, last verified on October 9, 2026. Nothing you type leaves your browser.
It covers mail within the United States: wedding invitations, save-the-dates, greeting cards, holiday cards and handmade cards. If a piece turns out to be a package, the calculator says so and points you to USPS instead of guessing a price.
USPS does not price by occasion. A bridal shower, baby shower, birthday or graduation party invitation follows exactly the same rules as a wedding suite, and so does a stack of holiday cards. Only the envelope's size, shape, weight and stiffness count, so one check here covers whatever you are sending this year.
The three mail classes
Almost every invitation falls into one of these:
- Standard letter. A flexible rectangle up to 6 1/8 x 11 1/2 in, no thicker than 1/4 in and no heavier than 3.5 oz. It costs $0.82 for the first ounce and $0.29 for each ounce after: $1.11 at 2 oz, $1.40 at 3 oz.
- Nonmachinable letter. A letter the sorting machines cannot handle. It pays the same letter price plus a flat $0.49 surcharge, so $1.31 at 1 oz and $1.60 at 2 oz.
- Large envelope (flat). Anything taller, longer, thicker or heavier than a letter, up to 12 x 15 in and 13 oz. It starts at $1.69 and must be flexible.
The common traps
Most surprise postage comes from a short list of design choices. None of them is obvious until someone tells you.
- Square envelopes. Machines need an envelope that is clearly longer than it is tall. Every square pays the surcharge.
- Wax seals and ribbon. A lump or a tie on the envelope means hand sorting.
- Rigid cards. Acrylic, wood and stiff board do not bend around the rollers.
- The address on the short side. The same envelope passes or fails depending on which way you write on it.
- One tenth of an ounce. Weight is rounded up, so 1.1 oz pays the 2 oz price.
How to avoid extra postage
Pick a rectangular envelope such as an A7 for a 5 x 7 invitation. Address it along the long side. Keep everything inside flat and flexible, and close it with the gummed flap. Then weigh one finished invitation and trim anything that puts it barely over an ounce line.
Do that and a 1 oz invitation costs $0.82. For 150 invitations that is $123.00, against $196.50 for the same list in square envelopes. The surcharge guide goes through every trigger.
If the square envelope or the wax seal is the whole point, pay the $0.49 and enjoy it. The surcharge is charged once per piece, so a second or third trigger costs nothing more.
Before you buy stamps
Assemble one complete invitation, weigh it, and run it through the calculator. Then take that one sealed sample to a post office counter and ask them to confirm. A clerk makes the final call on things like stiffness, and two minutes there protects the whole batch.
Remember the reply envelopes too. Each needs its own $0.82 stamp, and the stamped reply envelope adds weight to the invitation it travels in.
Look up your case
Questions and answers
How much is postage for a wedding invitation?
$0.82 if it weighs 1 oz or less, $1.11 up to 2 oz and $1.40 up to 3 oz, in a standard rectangular envelope. Add $0.49 if the envelope is square, rigid, or has a wax seal or ribbon.
Is invitation postage the same for showers and party invitations?
Yes. USPS prices mail by size, weight and shape, not by occasion. A shower, birthday or holiday invitation in a standard rectangular envelope costs $0.82 at 1 oz, the same as a wedding invitation, and the $0.49 surcharge applies in the same cases.
Why do square envelopes cost more to mail?
Sorting machines need an envelope whose length is at least 1.3 times its height. A square is 1 to 1, so it is sorted by hand and pays a $0.49 nonmachinable surcharge.
Does a wax seal need extra postage?
Yes. A raised seal makes the envelope uneven in thickness, which makes it nonmachinable. That adds $0.49, so a 1 oz invitation with a seal costs $1.31.
How much does a 2 oz invitation cost to mail?
$1.11 in a standard rectangular envelope, or $1.60 if it is nonmachinable. One Two-Ounce stamp covers the standard price exactly.
Do I need extra postage for a ribbon or bow?
Yes if the ribbon is on the outside of the envelope or leaves a lump you can feel. Both make the letter nonmachinable and add $0.49. A flat ribbon or paper band inside adds only its weight.
What is the nonmachinable surcharge?
It is an extra $0.49 per letter for envelopes that cannot go through USPS sorting machines. It is charged once per piece, whatever the weight and however many reasons apply.
What envelope size avoids extra postage?
Any rectangle whose long side is 1.3 to 2.5 times its short side, up to 6 1/8 x 11 1/2 in. The common A1, A2, A6, A7, A7.5, A9, A10 and #10 envelopes all qualify.
How do I weigh invitations without a postal scale?
Use a digital kitchen scale, or weigh ten finished invitations together and divide by ten. A post office will also weigh one for free. One ounce is 28.35 grams.
How much postage do RSVP envelopes need?
One Forever stamp, $0.82, for a standard reply envelope. A reply postcard with no envelope needs only $0.65.
Can I use two Forever stamps instead of a special stamp?
Yes. Two Forever stamps are worth $1.64, which covers a 2 oz letter ($1.11), a 3 oz letter ($1.40) or a 1 oz nonmachinable letter ($1.31). You overpay a little each time.
When do postage rates change?
USPS sets the dates and announces changes in advance. The prices on this site are from the price list effective October 4, 2026 and were last verified on October 9, 2026. Forever stamps stay valid through any change.
What happens if I don't put enough postage on an invitation?
It is short paid. USPS may deliver it with postage due from your guest, or return it to you. Short-paid nonmachinable letters, such as square or wax-sealed ones, are returned to the sender.
How many stamps does a wedding invitation need?
One, if you match the stamp to the weight: a Forever stamp for 1 oz, a Two-Ounce stamp for 2 oz or a Three-Ounce stamp for 3 oz.
How much postage for a 5x7 invitation?
A 5 x 7 invitation in an A7 envelope needs $0.82 at 1 oz, $1.11 at 2 oz and $1.40 at 3 oz. The A7 size itself never adds a surcharge.
Is this calculator affiliated with USPS?
No. This is an independent site. Its rates and rules are read from published USPS sources, and each result links to the rule it relies on.
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