01 / Planning the purchase
Keep the measurement with its unit
Length references can be copied between documents using different unit systems. This calculator converts a single length between millimetres, centimetres and inches. It is a mathematical aid for reading and communicating a value, rather than a method for choosing a material or deciding whether it fits a production process.
02 / Planning the purchase
The conversion rules
One centimetre equals 10 millimetres. One inch equals exactly 25.4 millimetres. Divide millimetres by 25.4 to obtain inches, or multiply inches by 25.4 to obtain millimetres. The tool uses these relations before rounding the values shown on screen.
03 / Planning the purchase
Worked arithmetic example
Enter 25.4 and choose millimetres. The tool returns 2.54 centimetres and 1 inch. This is an arithmetic example rather than an offered fiber length. To convert a different value, replace the number and select its original unit. Results update as soon as the input changes.
04 / Planning the purchase
Avoid unit and rounding mistakes
Read the original unit rather than guessing from the size of the number. If a value is expressed as a fraction of an inch, convert the fraction to a decimal before entering it. Preserve the original document value in your notes, especially if it was already rounded. Copying a converted number without its unit removes essential context.