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Envelope sizes

Also called: 封筒, envelope

Envelope size follows from what goes inside. For a US Letter sheet folded in three, the business envelope is the #10 (4.125 × 9.5 in). Its ISO counterpart for A4 folded in three is DL (110 × 220 mm); C5 (162 × 229 mm) takes A4 folded once, and C4 (229 × 324 mm) takes A4 flat. Japan's Naga 3 (120 × 235 mm) and Korea's small envelope (220 × 105 mm) do the same job for folded A4.

Envelope printing cannot be described by a single size. Flap shape and glue areas vary by envelope style and by printer, so the printable area comes from the printer's flat (die-line) template. On window envelopes, the window position decides where the recipient's address sits.

There is no national standard size for this product; every print shop sells its own sizes. The sizes below are common examples — download the template from the shop you order from before you start.

Sizes at a glance

SizeRegionTrim sizeBleedSafe
US #10United States9.5 × 4.13 in (241.3 × 104.78 mm)—9.5mm
DLEurope · International220 × 110 mm—10mm
C5Europe · International229 × 162 mm—10mm
C4Europe · International324 × 229 mm—10mm
Japan Naga 3Japan235 × 120 mm—10mm
Japan Kaku 2Japan240 × 332 mm—10mm
Korea largeKorea245 × 330 mm—10mm
Korea letterKorea220 × 105 mm—10mm

Bleed is how far artwork must extend past each trim edge; safe is how far inside the trim line text and logos should stay. Print shops ask for slightly different values, so always follow the file guide of the shop you order from.

Diagrams

241.3 mm104.78 mm
  • Trim
  • Safe line 9.53mm

US #10 9.5 × 4.13 in (241.3 × 104.78 mm)

The standard business envelope, for Letter folded in three.

Source: en.wikipedia.org

220 mm110 mm
  • Trim
  • Safe line 10mm

DL 220 × 110 mm

The international standard (ISO 269) for A4 folded in three.

Source: en.wikipedia.org

229 mm162 mm
  • Trim
  • Safe line 10mm

C5 229 × 162 mm

Holds A4 folded once, or A5 flat.

Source: en.wikipedia.org

324 mm229 mm
  • Trim
  • Safe line 10mm

C4 324 × 229 mm

Holds A4 unfolded.

Source: en.wikipedia.org

235 mm120 mm
  • Trim
  • Safe line 10mm

Japan Naga 3 235 × 120 mm

For A4 folded in three. The largest size in Japan's standard postal class.

Source: en.wikipedia.org

240 mm332 mm
  • Trim
  • Safe line 10mm

Japan Kaku 2 240 × 332 mm

Source: en.wikipedia.org

245 mm330 mm
  • Trim
  • Safe line 10mm

Korea large 245 × 330 mm

Holds A4 unfolded.

Secondary sourceSource: bizfactory.co.kr

220 mm105 mm
  • Trim
  • Safe line 10mm

Korea letter 220 × 105 mm

For A4 folded in three. Available in standard, jacket and window styles.

Secondary sourceSource: bizfactory.co.kr

Online print shops for envelopes

A neutral list — no partnerships, no affiliate links. We confirmed each site was online on 2026-09-22; check prices and shipping on the site itself.

United States

Europe

Japan

Korea