By Mustafa Bilgic · Last updated 26 June 2026

Wedding Invitation Postage Calculator

Work out exactly how many stamps your invitations need and what the postage will cost — using current 2026 USPS First-Class rates, including the square-envelope surcharge and pre-stamped RSVP returns most couples forget.

Quick answer: A standard 1-ounce invitation needs one $0.78 Forever stamp. A typical 2-ounce suite with inserts costs $1.07. A square envelope adds a $0.49 non-machinable surcharge. Use the calculator below for your exact totals.

Weight of one assembled invitation

Envelope shape

Number of invitations to mail

Pre-stamp RSVP return envelopes?

Based on 2026 USPS First-Class Mail letter rates: $0.78 first ounce, +$0.29 each additional ounce, +$0.49 non-machinable (square) surcharge. RSVP returns are figured at one $0.78 stamp each. Always weigh a finished invitation at the post office before buying in bulk.

2026 USPS rates this calculator uses

Mailpiece	2026 postage	Stamps (Forever = $0.78)
Rectangle, up to 1 oz	$0.78	1 Forever stamp
Rectangle, up to 2 oz	$1.07	1 Forever + 1 additional-ounce
Rectangle, up to 3 oz	$1.36	1 Forever + 2 additional-ounce
Square, up to 1 oz	$1.27	1 Forever + non-machinable surcharge
Square, up to 2 oz	$1.56	Forever + 1 oz + surcharge

Rates verified against USPS First-Class Mail pricing in effect for 2026: the Forever stamp held at $0.78 in January 2026, each additional ounce is $0.29, and the non-machinable surcharge for square or rigid letters is $0.49. USPS has filed for a Forever stamp increase to roughly $0.82 from mid-July 2026 (pending regulatory approval), so if you are buying stamps after that change, add four cents per stamp. When in doubt, buy Forever stamps — they stay valid at the new first-ounce price even after a rate rise.

Why square invitations cost more

USPS sorting machines can't process square envelopes, rigid invitations, or anything with a clasp, ribbon, wax seal, or uneven thickness. These are flagged non-machinable and must be hand-sorted, which adds the $0.49 surcharge per piece. On a 75-invitation order, choosing a square shape over a rectangle adds about $37 in postage alone — worth knowing before you fall in love with a square design. A clean rectangular invitation on standard stock is the single easiest way to keep postage at the base rate.

The postage most couples forget

The RSVP return envelope. Etiquette is to stamp it for your guests. That doubles the postage on every reply card — this calculator adds it automatically.
Save-the-dates. A separate, earlier mailing — usually a flat postcard, which mails at the $0.56 postcard rate rather than the letter rate.
Outer + inner envelopes. Only the outer envelope is mailed and needs postage, but the extra paper adds weight that can tip you into the next ounce.
Spare stamps. Buy 10–15% extra for re-mails, returned mail, and last-minute additions.

Keep postage low — start with a clean design

Design a standard-size, standard-weight invitation in the free editor and you stay at the base postage rate. No account, no watermark, print-ready download.

Open the free editor →

Frequently asked questions

How many stamps do I need for a wedding invitation?

A standard rectangular invitation under 1 ounce needs one $0.78 Forever stamp (2026 USPS rate). A full suite with RSVP card and details inserts usually weighs about 2 ounces, needing $1.07 of postage. Square invitations add a $0.49 non-machinable surcharge, so a 1-ounce square invitation costs $1.27 to mail.

How much does it cost to mail a square wedding invitation in 2026?

Square envelopes are non-machinable, so USPS adds a $0.49 surcharge on top of the weight-based rate. A 1-ounce square invitation costs $0.78 + $0.49 = $1.27; a 2-ounce square suite costs $1.07 + $0.49 = $1.56 (2026 rates).

Do I need extra postage for the RSVP return envelope?

Yes — etiquette is to pre-stamp the RSVP return envelope so guests can reply without buying a stamp. Budget one Forever stamp ($0.78) per reply envelope on top of your outgoing postage.

Should I weigh my invitation before buying stamps?

Always. Take one fully assembled invitation — outer envelope, invitation, all inserts and the reply envelope — to a post office and have it weighed. Inserts and thick paper push many suites over 1 ounce, and buying the wrong postage means returned or delayed mail.