Convert Inch to Microinch
Convert inches to microinches instantly. 1 inch = 1000000 microinch — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Microinch to Inch converter for the reverse conversion.
Units explained
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.
Microinch
A microinch is an Imperial unit of length equal to one millionth of an inch (2.54×10⁻⁸ m). It is used almost exclusively in surface-finish specifications for precision machining and optical components.
The microinch is derived from the inch using the SI-style prefix micro- to denote one millionth. Standardised through the 1959 International Yard and Pound Agreement, which fixed the inch at exactly 25.4 mm.
Microinches express surface roughness (Ra values) in US-based precision manufacturing — typical machined surfaces are 16–125 µin. Optical components and bearing races are often specified to 1–4 µin Ra.
Used in US precision-manufacturing literature throughout the 20th century; value became exact in 1959 when the inch was fixed at 25.4 mm via the International Yard and Pound Agreement.
Inch to Microinch conversion formula
The relationship between inches and microinches:
To convert inches to microinches, multiply the value in inches by 1000000. To reverse, multiply microinches by 1e-6.
How to use this converter
Type a value into the calculator. The result in microinches updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Microinch to Inch converter for the reverse direction.
Step-by-step: convert inches to microinches
- Write down the value in inches (in).
- Multiply that value by the factor 1000000.
- The product is the equivalent value in microinches (µin).
- To reverse, multiply the microinch value by 1e-6.
Worked examples
Example 1 — Convert 1 in to µin:
1 × 1000000 = 1000000 µin
Example 2 — Convert 100 in to µin:
100 × 1000000 = 1e+8 µin
Real-world example — Small-scale to atomic-scale
One inch equals 10 million microinches — useful for physics curricula that relate everyday measurements to atomic and optical scales.
1 in × 1000000 = 1000000 µin
Real-world example — Centimeter to wavelength scale
One inch equals 10 million microinches. Physics curricula use this kind of conversion to relate everyday measurements to atomic and optical scales.
1 in × 1000000 = 1000000 µin
Inch to Microinch conversion table
Standard reference values for converting inches to microinches:
| Inch [in] | Microinch [µin] |
|---|---|
| 0.01 | 10000 |
| 0.1 | 100000 |
| 1 | 1000000 |
| 2 | 2000000 |
| 3 | 3000000 |
| 4 | 4000000 |
| 5 | 5000000 |
| 10 | 1e+7 |
| 20 | 2e+7 |
| 30 | 3e+7 |
| 40 | 4e+7 |
| 50 | 5e+7 |
| 100 | 1e+8 |
| 500 | 5e+8 |
| 1000 | 1e+9 |
Frequently asked questions
How many microinches is 1 inch?
How do I convert inches to microinches?
How do I convert microinches back to inches?
How many microinches is 100 inches?
Popular length unit conversions
Convert Inch to other length units
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Metric / SI (18 units)
Imperial / US Customary (26 units)
Nautical (1 units)
Astronomical (9 units)
Atomic / Physics (6 units)
Typographic (3 units)
Sources & references
Conversion factor (1 in = 1000000 µin) 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.