C Envelope Sizes Table

The following table gives the sizes of each of the ISO 216 C envelope sizes in millimetres (mm), centimetres (cm), metres (m), inches (in) and feet (ft).

 Size L x W mm L x W cm L x W m L x W in L x W ft C0 1297 x 917 mm 129.7 x 91.7 cm 1.297 x 0.917 m 51.5 x 36.1 in 4.255 x 3.009 ft C1 917 x 648 mm 91.7 x 64.8 cm 0.917 x 0.648 m 36.1 x 25.5 in 3.009 x 2.126 ft C2 648 x 458 mm 64.8 x 45.8 cm 0.648 x 0.458 m 25.5 x 18.0 in 2.126 x 1.503 ft C3 458 x 324 mm 45.8 x 32.4 cm 0.458 x 0.324 m 18.0 x 12.8 in 1.503 x 1.063 ft C4 324 x 229 mm 32.4 x 22.9 cm 0.324 x 0.229 m 12.8 x 9.0 in 1.063 x 0.751 ft C5 229 x 162 mm 22.9 x 16.2 cm 0.229 x 0.162 m 9.0 x 6.4 in 0.751 x 0.531 ft C6 162 x 114 mm 16.2 x 11.4 cm 0.162 x 0.114 m 6.4 x 4.5 in 0.531 x 0.374 ft C7 114 x 81 mm 11.4 x 8.1 cm 0.114 x 0.081 m 4.5 x. 3.2 in 0.374 x. 0.266 ft C8 81 x 57 mm 8.1 x 5.7 cm 0.081 x 0.057 m 3.2 x 2.2 in 0.266 x 0.187 ft C9 57 x 40 mm 5.7 x 4.0 cm 0.057 x 0.040 m 2.2 x 1.6 in 0.187 x 0.131 ft C10 40 x 28 mm 4.0 x 2.8 cm 0.040 x 0.028 m 1.6 x 1.1 in 0.131 x 0.092 ft

C Envelope Sizes Chart

Based on chart from Office 365 Stationery

The chart to the right shows the relationships and relative sizes of the ISO 216 C envelope sizes, showing how each of the sizes is half the size of the size above it.

Formal Definition

ISO 216 specifies C envelope sizes as follows:

C(n) is the geometric mean of A(n) and B(n). Thus C4 is the geometric mean of A4 and B4 sizes.

All sizes are rounded to the nearest millimetre as the root 2 aspect ratio doesn't give whole numbers.

Formal Tolerances

The following formal tolerances are specified by ISO 216 for general production environments.

±1.5 mm (±0.06 in) for sizes up to 150 mm (5.9 in)

±2 mm (±0.08 in) for sizes between 150 and 600 mm (5.9 to 23.6 in)

±3 mm (±0.12 in) for sizes above 600 mm (23.6 in)

These tolerances are the same as for A & B paper sizes.

Notes

C envelope sizes also have an aspect ratio between length and width of 1:root2.

A C(n) envelope is design to hold an A(n) piece of paper unfolded, so a C4 envelope will hold an A4 piece of paper unfolded. This feature has given rise to the terms A3 envelope, A4 envelope, A5 envelope etc, that are used by people who are unaware of the ISO C series envelope sizes.

This feature also means that a C(n-1) envelope will hold an A(n) piece of paper folded in half once, a C(n-2) envelope will hold an A(n) piece of paper folded in half twice and so on.