Convert Microinch to Chain
Convert microinches to chains instantly. 1 microinch = 1.262626e-9 chain — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Chain to Microinch converter for the reverse conversion.
Units explained
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.
Chain
A chain is an Imperial unit of length equal to 66 feet (20.1168 m), or exactly 4 rods or 100 links. It is the central unit in the Gunter chain-based land-survey system.
Defined by Edmund Gunter in 1620 specifically to make land-area arithmetic easy: 10 square chains = 1 acre exactly. The 66-foot length and 100-link subdivision were chosen so chain measurements could be added decimally.
Chains are the fundamental unit of legacy US public land surveys (the entire US township-and-range system uses chains). Modern survey work generally uses meters or feet, but legacy deeds remain in chains.
Invented by Edmund Gunter in 1620; standardised throughout English and American land survey; became exact via the 1959 International Yard and Pound Agreement.
Microinch to Chain conversion formula
The relationship between microinches and chains:
To convert microinches to chains, multiply the value in microinches by 1.262626e-9. To reverse, multiply chains by 7.92e+8.
How to use this converter
Type a value into the calculator. The result in chains updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Chain to Microinch converter for the reverse direction.
Step-by-step: convert microinches to chains
- Write down the value in microinches (µin).
- Multiply that value by the factor 1.262626e-9.
- The product is the equivalent value in chains (ch).
- To reverse, multiply the chain value by 7.92e+8.
Worked examples
Example 1 — Convert 1 µin to ch:
1 × 1.262626e-9 = 1.262626e-9 ch
Example 2 — Convert 100 µin to ch:
100 × 1.262626e-9 = 1.262626e-7 ch
Real-world example — Molecular dimensions
The diameter of small molecular structures (around 2 microinches) is often converted into related sub-micron units when comparing measurements across different microscopy techniques or imaging modalities.
2 µin × 1.262626e-9 = 2.525253e-9 ch
Real-world example — Wavelengths across the spectrum
Optical and atomic-scale phenomena are routinely cross-converted between sub-micron units. A photon of wavelength 800 microinches can be re-expressed in chains for direct comparison with another instrument's calibration data sheet.
800 µin × 1.262626e-9 = 1.010101e-6 ch
Microinch to Chain conversion table
Standard reference values for converting microinches to chains:
| Microinch [µin] | Chain [ch] |
|---|---|
| 0.01 | 1.262626e-11 |
| 0.1 | 1.262626e-10 |
| 1 | 1.262626e-9 |
| 2 | 2.525253e-9 |
| 3 | 3.787879e-9 |
| 4 | 5.050505e-9 |
| 5 | 6.313131e-9 |
| 10 | 1.262626e-8 |
| 20 | 2.525253e-8 |
| 30 | 3.787879e-8 |
| 40 | 5.050505e-8 |
| 50 | 6.313131e-8 |
| 100 | 1.262626e-7 |
| 500 | 6.313131e-7 |
| 1000 | 1.262626e-6 |
Frequently asked questions
How many chains is 1 microinch?
How do I convert microinches to chains?
How do I convert chains back to microinches?
How many chains is 100 microinches?
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Imperial / US Customary (26 units)
Sources & references
Conversion factor (1 µin = 1.262626e-9 ch) 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.