Micrometers to Inches
An instant micrometers-to-inches converter, with the formula and a reference table below.
| Micrometers | Inches |
|---|---|
| 1 µm | 3.93701e-05 in |
| 2 µm | 7.87402e-05 in |
| 3 µm | 0.000118 in |
| 5 µm | 0.000197 in |
| 10 µm | 0.000394 in |
| 25 µm | 0.000984 in |
| 50 µm | 0.001969 in |
| 100 µm | 0.003937 in |
How to use
- Enter a value in the Micrometers field.
- The Inches figure appears immediately — no button to press.
- Typing in the Inches field converts back to Micrometers the same way.
- Use the reference table for the values that come up most often.
Micrometers to Inches formula
To convert micrometers to inches, multiply by 3.93700787e-05.
in = µm × 3.93700787e-05
Read in reverse, one inch is exactly 25,400 micrometers.
Why this factor: the micrometer and the inch are both defined against the meter, so dividing one definition by the other gives 3.93700787e-05 directly. Both definitions are set out in full below.
To go the other way, divide by 3.93700787e-05 — or use the Inches to Micrometers converter, which is the same calculation reversed.
Worked example
Start with 100 µm. Multiply by 3.93700787e-05 to get 0.003937 in.
100 µm × 3.93700787e-05 = 0.003937 in
The converter above does this for any value you type, in either direction.
What is a micrometer?
A micrometer, or micron, is one millionth of a meter — the scale of cells, fibers and semiconductor features.
Definition: Exactly 1×10⁻⁶ meter by SI prefix definition. Symbol µm.
Where it is used: Filtration ratings, particulate sizes (PM2.5 is 2.5 µm), fiber diameters, optical wavelengths.
Worth knowing: Often written 'micron' in industry. A human hair is roughly 70 µm across.
What is an inch?
An inch is one twelfth of a foot, used for small dimensions and for screen and wheel sizes globally.
Definition: Exactly 25.4 millimeters since the 1959 International Yard and Pound Agreement — an exact, not approximate, relation.
Where it is used: Screen diagonals, pipe and fastener sizes, tire and wheel diameters, and print layout worldwide.
Micrometers vs Inches
The micrometer is a metric unit while the inch is an imperial unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many inches are in a micrometer?
One micrometer equals 3.93700787e-05 inches.
What is the formula to convert micrometers to inches?
Multiply the number of micrometers by 3.93700787e-05. To reverse it, divide by 3.93700787e-05 instead.
How do I convert inches back to micrometers?
Divide by 3.93700787e-05, which is the same as multiplying by 25400.
How many inches are in 10 micrometers?
10 µm works out to 0.000394 in.
Is there anything to watch out for with micrometers?
Often written 'micron' in industry. A human hair is roughly 70 µm across.
How is the micrometer defined?
Exactly 1×10⁻⁶ meter by SI prefix definition. Symbol µm.