On their own, double envelopes will not necessarily require additional postage. However, the United States Postal Service uses standard shape and size parameters to determine whether an envelope will require additional postage. Essentially, if the dimensions or weight of your invitation ensembles fall outside of these parameters, then they will cost more to mail.

When Double Envelopes Will Require Additional Postage

• If they are square: Square double envelopes will automatically require additional postage, as the USPS considers square mail to be an “unusual shape” that falls outside of the standard parameters.
• If they weigh over one ounce: Mail that weighs one ounce or less does not require additional postage, but mail that weighs over one ounce will.

If your invitation ensemble consists of rectangular double envelopes and just one invitation card, it will most likely weigh under one ounce, and will need just one stamp. However, adding response items and additional insert cards to your ensemble typically brings the weight over one ounce. The additional postage cost for this will vary with exact weight.

In all cases, we recommend bringing a finished invitation ensemble to your local post office prior to mailing. This way, you can be sure your wedding envelopes have the correct amount of postage, and will not be marked with an unattractive “Return to Sender” stamp.

We also recommend asking your local post office to hand cancel your invitations