Designing Certificates and Prints to Fit Perfectly in Rigid Envelopes
Size your prints and certificates to fit standard rigid envelopes perfectly every time.
Standard envelope sizes
Quick answer
Design prints 5-10mm smaller than the envelope internal dimensions on each side. An A4 print (297 x 210mm) fits a C4 board-backed envelope (internal approximately 320 x 225mm) with comfortable clearance. For certificates, allow extra margin for any embossing or raised seals. Add a sheet of tissue paper or glassine between prints and the envelope face to prevent scuffing.
Margin and clearance
Too tight and insertion is difficult. Too loose and contents shift.
The rigid board adds 1-2mm per side, reducing usable dimensions.
Raised seals and embossing add thickness that affects fit.
Design tips
Keep important content away from the edges of your prints and certificates. A 15-20mm safe margin ensures nothing critical is at risk from envelope edges or handling damage. For prints sold in multiple sizes, design your size range around standard envelope dimensions to avoid custom packaging.
Sending safely: certificate posting guide or packing and sealing.
Extra protection
Protection additions0 / 4 checked
Board-backed envelopes for prints
C4 and C3 do not bend envelopes sized for standard print and certificate formats.
Browse do not bend envelopesFrequently asked questions
C4 (324 x 229mm) fits A4 flat with 5-10mm clearance per side.
C3 (458 x 324mm) fits A3 flat.
5-10mm per side between the print edge and envelope interior.
Yes, a sheet between the print and envelope face prevents scuffing and friction marks.
Yes, designing your size range around standard envelope dimensions avoids custom packaging costs.
Part of our guide
Product Guide: Do Not Bend Envelopes
Expert guides on rigid mailers and board-backed envelopes for protecting documents, prints, and certificates.
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