Will these envelopes fit??

I'm finally ordering invitations (as soon as everyone stops b*tching about the wording on them), but the invites I picked out are a self mailer. I personally like when an invitation comes in an envelope and want to get envelopes. I also figure the envelopes will be easier for me to address as I don't know how I would put the whole invite through the printer.

On the website, the ecru invite is measured at 6 1/4 x 6 1/4. Can I get envelopes that are the same size or should I get 6 1/2 x 6 1/2 to be safe. I just don't want to end up with envelopes that the invites are swimming in.

Here is the invite

I don't think 1/2 inch will make is swim...your carstock is thick and you have inserts which makes it thicker ... you want to have some room in there. Better for it to be a little but bigger then not fit at all...good luck!