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International Envelope Series



The C1 paper size, a member of the ISO 216 standard series, is an intriguing format that holds its own unique place in the world of print and design. This international standard, which includes A, B, and C series sizes, is widely adopted across the globe for its logical and practical system.

Measuring 648 x 917 millimeters or approximately 25.5 x 36.1 inches, C1 is primarily used for large-scale applications such as posters or architectural drawings. Its dimensions are precisely calculated by taking the geometric mean between two consecutive A-series sizes - a testament to the meticulous planning behind this standardized system.

C1 paper dimensions


View All International Envelope Series

2A046.81 x 66.221189 x 1682119 x 1683370 x 4768
A120.51 x 0.7113 x 181 x 237 x 51
4A066.22 x 93.621682 x 2378168 x 2384768 x 6741
A110.71 x 1.0218 x 262 x 351 x 74
A101.02 x 1.4626 x 373 x 474 x 105
A3+12.95 x 19.02329 x 48333 x 48933 x 1369
A1+23.98 x 35.98609 x 91461 x 911726 x 2591
A0+35.98 x 50.87914 x 129291 x 1292591 x 3662
A64.13 x 5.83105 x 14811 x 15298 x 420
A55.83 x 8.27148 x 21015 x 21420 x 595
A48.27 x 11.69210 x 29721 x 30595 x 842
A311.69 x 16.54297 x 42030 x 42842 x 1191
A91.46 x 2.0537 x 524 x 5105 x 147
A216.54 x 23.39420 x 59442 x 591191 x 1684
A82.05 x 2.9152 x 745 x 7147 x 210
A123.39 x 33.11594 x 84159 x 841684 x 2384
A72.91 x 4.1374 x 1057 x 11210 x 298
A033.11 x 46.81841 x 118984 x 1192384 x 3370

One fascinating aspect of C1 and other ISO paper sizes is their aspect ratio. Maintaining a constant ratio of √2 (approximately 1:1.414), these formats retain their shape when scaled up or down - a feature that greatly simplifies enlargement or reduction tasks in printing.

Moreover, within the envelope industry, C-series sizes like C1 play an essential role. They are designed to be slightly larger than their corresponding A-series counterparts to accommodate them perfectly - making them ideal for envelopes.

While it may seem mundane at first glance; delving deeper into its specifications reveals that every aspect of the C1 paper size has been carefully considered and optimized for practicality and efficiency.

Other Formats in the International Envelope Series

Interesting facts about C1

1: C1 paper is part of the ISO 216 standard

C1 paper is a specific size within the ISO 216 standard, which defines international paper sizes. It is commonly used for posters, architectural drawings, and other large format prints.

2: C1 paper measures approximately 648 x 917 millimeters

The dimensions of C1 paper are approximately 648 x 917 millimeters or about 25.5 x 36.1 inches. Its large size makes it suitable for displaying detailed designs or artwork.

3: C1 paper is equivalent to two A2 sheets

In terms of area, C1 paper is equivalent to two A2 sheets placed side by side. This means that you can print larger designs on a single sheet without having to join multiple smaller sheets together.

4: The aspect ratio of C1 paper is √2:1

The aspect ratio of C1 paper (and all ISO sizes) is √2:1, which means that if you divide the longer side by the shorter side, you will always get the square root of two (approximately equal to 1.414).

5: The origin of ISO standard dates back to Germany in the early twentieth century

The ISO standard for paper sizes has its roots in a German standard called DIN (Deutsche Industrie Norm). It was first introduced in Germany in the early twentieth century and later adopted internationally as ISO standards.

6: The purpose behind standardized sizes was efficiency and waste reduction

The adoption of standardized sizes like C1 was driven by the need for efficiency and waste reduction in printing processes. Standard sizes allow for better planning, compatibility, and reduced paper waste during production.

7: C1 paper is not commonly found in everyday office use

Due to its large size, C1 paper is not commonly used in everyday office printing. It is more frequently utilized by professional printers, architects, engineers, and designers who require larger format prints.

8: C1 paper can be easily scaled down to smaller sizes

If a smaller size is needed while maintaining the same aspect ratio as C1 paper, it can be easily scaled down using the ISO standard. For example, cutting a C1 sheet in half along its longer side results in two C2 sheets.

9: The ISO standard includes both A and B series of paper sizes

In addition to the A series (which includes A0, A1, A2), and the C series (which includes C0, C1), the ISO standard also defines B series sizes. The B series sits between the A and C series in terms of dimensions.

10: The ISO standard has been widely adopted globally

The ISO standard for paper sizes has been widely adopted around the world. It simplifies international communication and printing processes by providing a consistent framework for determining appropriate paper dimensions.