Resources Wedding & event stationery Free tool
Envelope & invitation size finder
Pick your card size and insert count: get the matching envelope, stack thickness, USPS machinability and which enclosure cards nest inside.
Envelope & invitation size finder
Main card size
Pieces in the envelope
Card stock
Outer envelope
A7 (5.25 × 7.25)
Fits 5" × 7" with ¼" clearance
Stack thickness
≈ 0.076"
Machinable letter (≤ ¼")
Nesting inserts
A2 · A6
Cards that sit inside without touching the edges
Rule of thumb: envelope = card + ¼" each way. Inner cards step down one size (A7 → A6 details → A2 RSVP → A1 RSVP envelope). Belly bands and vellum jackets add ≈ 0.01" each.
Designers & agencies: put this calculator on your own site — free, always up to date.
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