C5 envelope size in mm, cm and inches
C5 envelope is 162 × 229 mm (6.38 × 9.02 inches).
C5 envelope dimensions
| Unit | Width | Length |
|---|---|---|
| Millimetres | 162 mm | 229 mm |
| Centimetres | 16.2 cm | 22.9 cm |
| Inches | 6.38 in | 9.02 in |
| Points (1/72 in) | 459 | 649 |
Shape: length is 1.414 times the width.
C5 is the middle of the common ISO 269 C sizes: C4 is twice its area, C6 is half. It is the envelope for A5 sheets and for A4 folded once.
What fits in a C5 envelope envelope
The first fold that leaves at least 3 mm to spare each way is shown. “Does not fit” means no fold up to quarters fits.
| Sheet | How it fits | Size when folded | Spare (width, length) |
|---|---|---|---|
| A3 | folded in quarters | 148 × 210 mm | 14 × 19 mm |
| A4 | folded in half | 210 × 148 mm | 14 × 19 mm |
| A5 | flat | 148 × 210 mm | 14 × 19 mm |
| A6 | flat | 105 × 148 mm | 57 × 81 mm |
| US Letter | folded in half | 216 × 140 mm | 22 × 13 mm |
| US Legal | folded in three (letter fold) | 216 × 119 mm | 43 × 13 mm |
| Half Letter (Statement) | flat | 140 × 216 mm | 22 × 13 mm |
Spare is the envelope dimension minus the folded sheet, in mm. Real envelopes vary a little between makers, and a thick insert needs extra room.
A5 flat, A4 folded in half
A5 (148 × 210 mm) goes in a C5 envelope with 14 mm spare across and 19 mm along. A4 folded once, across the middle, becomes A5, so it fits too: that makes C5 the usual choice for a letter with a few pages that you do not want folded in three.
C5 or C6/C5?
C6/C5 (114 × 229 mm) is narrower; it is for letters folded in three. If your letter is folded once, C5 is the right size.
B5 and B6 sheets
A B5 sheet (176 × 250 mm) does not fit in C5 flat. Folded in half it becomes B6 (125 × 176 mm) and fits with 37 mm spare across and 53 mm along. A B6 sheet goes in C5 flat.
Postage note
Check the postal operator's size limits for your country before relying on size alone: sheet size does not decide the postage band, but envelope outer dimensions and thickness often do.
Frequently asked questions
What size is C5 in cm?
C5 is 16.2 x 22.9 cm (162 x 229 mm).
What size is a C5 envelope in inches?
A C5 envelope is 6.38 x 9.02 inches.
Does A4 fit in a C5 envelope?
Folded in half, yes: A4 folded once is 148 x 210 mm (A5), leaving 14 mm and 19 mm to spare. Flat A4 needs a C4 envelope.
Is C5 the same as A5?
No. A5 is the paper size (148 x 210 mm); C5 is the envelope for it (162 x 229 mm).
How many C5 envelopes make one C4?
C5 is half of C4 by area, so two C5 envelopes cover the same area as one C4.