Mils to Micrometers Converter
Enter the length in mils below to convert it to micrometers.
Convert Mils to Micrometers
Enter a value in mils (mil) to convert to micrometers (µm).
Mils to Micrometers Conversion Chart (1–40 Continuous)
Continuous 1 to 40 mils lookup table with exact decimals and reduced nearest 1/64 fractions. Highlighted rows mark common shop and ruler values.
| Mils (mil) | Decimal (µm) | Fraction — Nearest 1/64 (Reduced) | Nearest 1/16 (Tape) |
|---|---|---|---|
1 mil★ Common | 25.4 µm | 25 13/32 µm | 25 3/8 µm |
2 mil★ Common | 50.8 µm | 50 51/64 µm | 50 13/16 µm |
3 mil★ Common | 76.2 µm | 76 13/64 µm | 76 3/16 µm |
4 mil | 101.6 µm | 101 19/32 µm | 101 5/8 µm |
5 mil★ Common | 127 µm | 127 µm | 127 µm |
6 mil★ Common | 152.4 µm | 152 13/32 µm | 152 3/8 µm |
7 mil | 177.8 µm | 177 51/64 µm | 177 13/16 µm |
8 mil★ Common | 203.2 µm | 203 13/64 µm | 203 3/16 µm |
9 mil | 228.6 µm | 228 19/32 µm | 228 5/8 µm |
10 mil★ Common | 254 µm | 254 µm | 254 µm |
11 mil | 279.4 µm | 279 13/32 µm | 279 3/8 µm |
12 mil★ Common | 304.8 µm | 304 51/64 µm | 304 13/16 µm |
How to Convert Mils to Micrometers
To convert mils to micrometers, multiply the length by the following conversion ratio: 25.4 micrometers/mil.
Since one mil is equal to 25.4 micrometers, you can use this simple formula to convert:
The length in micrometers is equal to the length in mils multiplied by 25.4.
For example, here's how to convert 5 mils to micrometers using the formula above.
How Many Micrometers Are in a Mil?
There are 25.4 micrometers in a mil, which is why we use this value in the formula above.
Our mil fraction and decimal calculator can convert mils and micrometers, and it automatically converts the results to US customary, imperial, and SI metric values.
Mils and micrometers are both units used to measure length. Keep reading to learn more about each unit.
How to Convert Mils to Fractional Inches (1/16″, 1/32″ & 1/64″)
Plain-language method for turning decimal inches into a standard tape-measure or machinist ruler fraction
Calculators give you a decimal number (such as 0.005 in), but tape measures and woodworking rulers are marked in binary fractions of an inch—most commonly 1/16″ on carpenter tapes, 1/32″ on fine woodworking rules, and 1/64″ on machinist scales.
Here is the step-by-step worked example for converting 5 mils (mil) into fractional inches:
- Find the decimal inches result: Convert 5 mil to inches to get 0.005 in.
- Separate the whole inches from the decimal part: Keep the whole number 0 aside, leaving the decimal remainder 0.005.
- Multiply the decimal part by your desired fraction denominator (16, 32, or 64) and round half up: Multiply 0.005 by 16, 32, or 64, then round to the nearest whole number (values ending in .5 round up).
- Reduce the fraction to lowest terms: If the rounded top number (numerator) is even, divide both top and bottom by 2 (or their Greatest Common Divisor) until the top number is odd, then combine with your whole inches.
What Is a Mil?
A mil is a unit of length equal to 0.0000254 meters (m), the base unit for length. One thousandth of an inch (0.001 in = 0.0254 mm), used in manufacturing tolerances and film thickness. [1]
The mil is classified as a US customary and imperial unit of length. Mils can be abbreviated as mil; for example, 1 mil can be written as 1 mil.
When working with mils (mil) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, mils (mil) are widely used across fine-tolerance laboratory, analytical, and micro-scale length measurements within US customary and imperial workflows, engineering documentation, and technical data sheets.
What Is a Micrometer?
A micrometer is a unit of length equal to 1/1,000,000 of a meter (0.000001 m). One millionth of a meter (10⁻⁶ m), also known as a micron. [2]
The micrometer is classified as a metric and SI-compatible unit of length. Micrometers can be abbreviated as µm; for example, 1 micrometer can be written as 1 µm.
In the metric system, "micro" is the standard SI prefix for millionths, or 10⁻⁶. This makes the micrometer (µm) a convenient decimal multiple of the meter (m).
In practice, micrometers (µm) are widely used across fine-tolerance laboratory, analytical, and micro-scale length measurements within SI metric workflows, engineering documentation, and technical data sheets.
When converting length between mils (mil) and micrometers (µm), keep full floating-point precision (1 mil = 25.4 µm; 1 µm = 0.0393701 mil) during intermediate calculations and round only the final micrometer figure to match your instrument tolerance.
More Mil & Micrometer Conversions
Need to calculate in the opposite direction? Use our micrometers to mils calculator to switch your starting unit immediately. You can also explore related tools such as converting micrometers to mils, converting inches to micrometers, or converting mils to millimeters.
Frequently Asked Questions
References
- [1]NIST OWM StandardNIST OWM (SI Units — Length)·Length Metrology Standard — Mils (mil) to Micrometers (µm)
- [2]BIPM SpecificationBIPM (SI Base Unit: Metre (m))·Unit Specifications: Mil (Thou) (mil) & Micrometer (Micron) (µm)
- [3]NIST HB 133 ReferenceNIST HB 133 (NIST Handbook 133 (2019 Ed.))·Conversion Factors & Mathematical Basis (mil to µm)