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.
ISO 216 specifies C envelope sizes as follows:
All sizes are rounded to the nearest millimetre as the root 2 aspect ratio doesn't give whole numbers.
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.
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.
DL Business Envelopes
The DL business envelope is not part of the ISO C envelope sizes but is the most commonly used international envelope size, being used for most business corresponce. The DL envelope also comes from tne German DIN standards, with its orginal name being DIN Lang. The DL envelope is 110 x 220 mm (4⅓" x 8⅔") in size and can take an A4 sheet of paper folded into thirds parallel to its shorter size.
ISO defined a C6/5 envelope at 114 x 229 mm at the behest of manufacturers of automatic envelope filling machines as the original DL size of 110 x 220mm was considered slightly to small for reliable automatic envelope filing when A4 paper is used. The C6/5 envelope hasn't been the success that had been hoped and the DL continues to be the most widely used size.