Millimeters to thou Converter

This page allows you to convert length values expressed in millimeters to their equivalent in thou.

Enter the value in millimeters in the top field (the one marked "mm"), then press the "Convert" button or the "Enter" key. The converter also works the other way round: if you enter the value in thou in the "thou" field, the equivalent value in millimeters is calculated and displayed in the top field.

Millimeters to Thou Conversion Formula

$L_{thou}=L_{millimeters} * \frac{5000}{127}$

Where Lmillimeters is the length in millimeters and Lthou is its equivalent in thou.

Reverse formula (thou to millimeters)


One millimeter, in the metric system, is equivalent to 1/1000 (one thousandth) of a meter. 1 mm = 10-3 m.

It is used to describe lengths that are relatively small, like the widths of pipes, cables or connectors. The well known terms 8mm, 16mm and 32mm describe common widths of motion picture films.

To understand the approximate size of one millimeter, see this tiny red line: 1mm line.    And this line should be approximately five millimeters long: 5mm line


The thou is a unit of measure for length equivalent to 1/1000 of an inch, that is 0.001 inches. It is also known as 'mil'. Introduced around 1844, it is still used today in manufacturing specifications of certain products such as printed circuit boards (ex. size of via holes and distance between lines), paper thickness (ex. newspaper paper thickness is around 2 to 4 thou), latex gloves. Reference: Wikipedia