C Series

Using Designs.ai extensive sizes list, browse and use the right sizes and dimensions of various C series envelopes.

Size Dimension (inch) Dimension (mm)
C0 36.1 x 5.11 in 917 x 129.7 mm
C1 25.51 x 36.1 in 648 x 917 mm
C2 18.03 x 25.51 in 458 x 648 mm
C3 12.76 x 18.03 in 324 x 458 mm
C4 9.02 x 12.76 in 229 x 324 mm
C5 6.42 x 9.02 in 163 x 229 mm
C6 4.49 x 6.38 in 114 x 162 mm
C7 3.19 x 4.49 in 81 x 114 mm
C8 2.24 x 3.19 in 57 x 81 mm
C9 1.57 x 2.24 in 40 x 57 mm
C10 1.1 x 1.57 in 28 x 40 mm

The C series is often used for envelopes and its sizes are defined in the ISO 269 paper size standard. The dimensions of the envelope of a C series falls in between A and B and frequently used to complement A and B papers. The C series paper would be the ideal paper to start if you are looking for an envelope to fit an A or B series paper.

In general, the A series paper fits into an envelope of the C series of the same number. This makes it best to go for the C4 envelope if you require an envelope for your A4 letter. If the same letter A4 is taken and it is folded into half, it becomes an A5. The most relevant size to be used will then be the C5 envelope, which is the same size as a C4 envelope folded in half.

The aspect ratio of the C series is 1:√2 which is similar to the A and B series. Every piece of paper can therefore be folded once or twice to fit well into a smaller envelope.

The most common envelopes for business use are the C4, C5, C6 and DL sizes.