"how do i know how much vintage postage i need?"

Great question that is best left to the pros at the US Post Office. You can take an assembled invitation to the post office to have it weighed & measured, and you can also use the USPS Postage Calculator to get a good estimate.

Here are some general guidelines to keep in mind:

  • Envelope Size: For your envelopes to qualify as a “Letter”, the envelope must meet the following guidelines:

    • The envelope must be rectangular, and must be at least 3-1/2” high, and 5” wide (an envelope that is 3” x 6” would not qualify because the shortest side is shorter than 3-1/2”).

    • The envelope also cannot be larger than 6-1/8” x 11-1/2’ (an envelope that is 6-1/2” x 9” would not qualify because the “shortest” edge is longer than 6-1/8”).

    • The nuances here can be confusing, so please take your envelope to the post office to confirm (more detail on USPS letter sizing here).

 
  • Non-Machinable Characteristics: If you are adding a wax seal, a button, external ribbon, or if you are writing the address sideways, or if you have an invitation that is “too rigid” (along with a handful of other nuances), you will likely also need to pay a “non-machinable surcharge” as your envelope will require hand processing. As this time, the surcharge is $0.21. Again, the recommendation is to take your fully asembled invitation to the post office to confirm. (more details on USPS non-machinable characteristics here)

If you are mailing a standard sized letter rectangular envelope that weighs less than 1 oz., you will need 1 "forever" stamp, or 50¢ worth of postage. Keep in mind that postage rates do fluctuate up and down over time, so double and triple check before you apply your vintage postage! There is a postage rate change scheduled for January 2019.

If you are mailing a square envelope that weighs less than 1 oz., or a rectangular envelope that weighs between 1-2 oz. (most wedding invitations) domestically, you will need 71¢ worth of postage.

...Yes, square envelopes cost more to mail than rectangular envelopes, and each additional ounce costs an additional amount...

...Yes, international envelopes also require additional postage...

...Check with your post office to be sure!