C Envelope Paper Sizes

The C series envelope sizes are defined in ISO 269. C envelopes are designed to hold A series paper: a C4 envelope holds an A4 sheet, a C5 holds A5 or a folded A4, etc.

C0917 × 1297mm C1648 × 917mm C2458 × 648mm C3324 × 458mm C4229 × 324mm C5162 × 229mm C6114 × 162mm C781 × 114mm C857 × 81mm C940 × 57mm C1028 × 40mm

All C Envelope Paper Sizes Dimensions

Size	Width × Height (mm)	Width × Height (in)	Width × Height (cm)
C0	917 × 1297	36.10 × 51.06	91.70 × 129.70
C1	648 × 917	25.51 × 36.10	64.80 × 91.70
C2	458 × 648	18.03 × 25.51	45.80 × 64.80
C3	324 × 458	12.76 × 18.03	32.40 × 45.80
C4	229 × 324	9.02 × 12.76	22.90 × 32.40
C5	162 × 229	6.38 × 9.02	16.20 × 22.90
C6	114 × 162	4.49 × 6.38	11.40 × 16.20
C7	81 × 114	3.19 × 4.49	8.10 × 11.40
C8	57 × 81	2.24 × 3.19	5.70 × 8.10
C9	40 × 57	1.57 × 2.24	4.00 × 5.70
C10	28 × 40	1.10 × 1.57	2.80 × 4.00