Convert Micrometer to Inch
Convert micrometers to inches instantly. 1 micrometer = 3.937008e-5 inch — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Inch to Micrometer converter for the reverse conversion.
Units explained
Micrometer
A micrometer (also called a micron) is a metric unit of length equal to one millionth of a meter (1×10⁻⁶ m). It is the standard unit for measuring microscopic dimensions in biology, materials science, and semiconductor manufacturing.
Defined alongside the meter when France adopted the metric system in 1795, using the SI prefix micro- (from Greek mikros, "small") to denote one-millionth.
Micrometers are used to measure cell sizes, bacteria, semiconductor process nodes, fiber diameters, dust particles, and wavelengths of infrared radiation. The diameter of a human hair is about 70 μm.
Defined in 1795 as part of the original French metric system; the name "micron" was officially deprecated by the BIPM in 1967 in favor of micrometer.
Inch
An inch is an Imperial and US customary unit of length defined since 1959 as exactly 25.4 millimeters (0.0254 meters). It is still the standard small unit of length in the United States, the United Kingdom (informally), and a few other countries.
The inch derives from the Roman uncia (one-twelfth of a foot) and survived through Anglo-Saxon and medieval English measurement systems. Various definitions persisted regionally until the 1959 International Yard and Pound Agreement standardized the inch globally as exactly 25.4 mm.
Inches are used in the US and UK for body height, screen sizes (TVs, monitors, phones), tire sizes, plumbing, lumber, paper sizes (US Letter is 8.5 × 11 in), and most consumer product specifications in the United States.
Anglo-Saxon origin (predating 1066); standardized to 25.4 mm exactly by the International Yard and Pound Agreement of 1959, signed by the US, UK, Canada, Australia, New Zealand, and South Africa.
Micrometer to Inch conversion formula
The relationship between micrometers and inches:
To convert micrometers to inches, multiply the value in micrometers by 3.937008e-5. To reverse, multiply inches by 25400.
How to use this converter
Type a value into the calculator. The result in inches updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Inch to Micrometer converter for the reverse direction.
Step-by-step: convert micrometers to inches
- Write down the value in micrometers (μm).
- Multiply that value by the factor 3.937008e-5.
- The product is the equivalent value in inches (in).
- To reverse, multiply the inch value by 25400.
Worked examples
Example 1 — Convert 1 μm to in:
1 × 3.937008e-5 = 3.937008e-5 in
Example 2 — Convert 100 μm to in:
100 × 3.937008e-5 = 0.0039370079 in
Real-world example — Paper-thickness specification
100-μm paper (about 3.9 mil) is a typical print-shop substrate. Converting μm to inches helps printers comparing European and US substrate datasheets, since both unit systems frequently appear on the same product page.
100 μm × 3.937008e-5 = 0.0039370079 in
Real-world example — Hair-width to imperial
A 75-μm-thick human hair measures 0.00295 inch (about 3 mil). Forensics labs and trichology researchers convert μm to inches when reporting findings to US-localised case files.
75 μm × 3.937008e-5 = 0.0029527559 in
Real-world example — Micrometer to mil scale
A 500-μm wire diameter (typical of light-gauge electrical wire) equals 0.0197 inch (about 20 mils). Electronics buyers translate μm to inches because some component datasheets cite gauge in μm (European convention) and others in inches or mils (US convention).
500 μm × 3.937008e-5 = 0.0196850394 in
Micrometer to Inch conversion table
Standard reference values for converting micrometers to inches:
| Micrometer [μm] | Inch [in] |
|---|---|
| 0.01 | 3.937008e-7 |
| 0.1 | 3.937008e-6 |
| 1 | 3.937008e-5 |
| 2 | 7.874016e-5 |
| 3 | 0.0001181102 |
| 4 | 0.0001574803 |
| 5 | 0.0001968504 |
| 10 | 0.0003937008 |
| 20 | 0.0007874016 |
| 30 | 0.0011811024 |
| 40 | 0.0015748031 |
| 50 | 0.0019685039 |
| 100 | 0.0039370079 |
| 500 | 0.0196850394 |
| 1000 | 0.0393700787 |
Frequently asked questions
How many inches is 1 micrometer?
How do I convert micrometers to inches?
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How many inches is 100 micrometers?
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Metric / SI (17 units)
Imperial / US Customary (7 units)
Nautical (1 units)
Sources & references
Conversion factor (1 μm = 3.937008e-5 in) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.