Wedding Invitation Postage Calculator

Envelope Details

Envelope Shape Square adds USPS surcharge

Standard Square

Destination

Domestic International

Weight

⚠️ Square envelopes require a USPS non-machinable surcharge of $0.49 per envelope.

Guest Count

Number of Invitations

How to Calculate Wedding Invitation Postage

Planning a wedding is stressful enough without having your beautiful invitations returned for insufficient postage. Many couples assume a standard Forever stamp will cover their heavy cardstock invites, only to discover hidden USPS fees. This calculator ensures you know the exact postage required before you mail your suite.

The Square Envelope Surcharge

One of the most common mistakes in wedding stationery involves the square envelope. The USPS relies on automated sorting machines designed for rectangular mail. If you send a square envelope, it must be hand-sorted, which immediately triggers a "non-machinable surcharge." For 2025, this adds an extra $0.49 to every single envelope. Our tool automatically factors this surcharge into your total when you toggle the shape.

Weight and Additional Ounces

A standard First-Class stamp covers the first ounce. However, once you add RSVPs, detail cards, wax seals, ribbons, and thick liners, wedding invitations easily push past that 1-ounce mark. Each additional ounce requires more postage. We highly recommend taking one fully assembled invitation to your local post office to be officially weighed before buying your vintage or custom stamps in bulk.