Convert Microinch to US Survey Foot
Convert microinches to us survey feet instantly. 1 microinch = 8.333317e-8 us survey foot — use the live calculator, the exact formula, a conversion table and worked examples. Also check the US Survey Foot 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.
US Survey Foot
The US Survey Foot is a legacy unit of length defined as exactly 1200/3937 meters (approximately 0.3048006 m). It differs from the modern international foot by about 2 parts per million.
Established in the United States by the Mendenhall Order of 1893, which defined the foot in terms of the meter as 1200/3937 m. The US continued using this value for surveying even after the 1959 International Yard and Pound Agreement standardized the international foot at exactly 0.3048 m.
Used in US land surveying, geodetic measurements, state plane coordinate systems, and legal land descriptions. The US Survey Foot was officially deprecated by NIST and NOAA effective December 31, 2022, with the international foot becoming the sole US standard. Legacy data and recorded land surveys still reference it.
Mendenhall Order of 1893 defined the foot as 1200/3937 m; persisted in US surveying after 1959; officially deprecated by NIST/NOAA as of December 31, 2022.
Microinch to US Survey Foot conversion formula
Note: this conversion uses a generally accepted modern value. Historical and regional definitions of this unit varied across times and places.
The relationship between microinches and us survey feet:
To convert microinches to us survey feet, multiply the value in microinches by 8.333317e-8. To reverse, multiply us survey feet by 1.200002e+7.
How to use this converter
Type a value into the calculator. The result in us survey feet updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the US Survey Foot to Microinch converter for the reverse direction.
Step-by-step: convert microinches to us survey feet
- Write down the value in microinches (µin).
- Multiply that value by the factor 8.333317e-8.
- The product is the equivalent value in us survey feet (sft).
- To reverse, multiply the us survey foot value by 1.200002e+7.
Worked examples
Example 1 — Convert 1 µin to sft:
1 × 8.333317e-8 = 8.333317e-8 sft
Example 2 — Convert 100 µin to sft:
100 × 8.333317e-8 = 8.333317e-6 sft
Real-world example — Bridging nine orders of magnitude
500 million microinches equals a value comfortably in the human-scale us survey feet range. Physics problems that span this gap are common when comparing the wavelength of light to the path length of an experiment.
5e+8 µin × 8.333317e-8 = 41.6665833333 sft
Real-world example — From sub-micron to human scale
One billion microinches equals one us survey foot — the conversion that drives home the gulf between atomic-scale features and everyday objects in physics curricula.
1e+9 µin × 8.333317e-8 = 83.3331666667 sft
Microinch to US Survey Foot conversion table
Standard reference values for converting microinches to us survey feet:
| Microinch [µin] | US Survey Foot [sft] |
|---|---|
| 0.01 | 8.333317e-10 |
| 0.1 | 8.333317e-9 |
| 1 | 8.333317e-8 |
| 2 | 1.666663e-7 |
| 3 | 2.499995e-7 |
| 4 | 3.333327e-7 |
| 5 | 4.166658e-7 |
| 10 | 8.333317e-7 |
| 20 | 1.666663e-6 |
| 30 | 2.499995e-6 |
| 40 | 3.333327e-6 |
| 50 | 4.166658e-6 |
| 100 | 8.333317e-6 |
| 500 | 4.166658e-5 |
| 1000 | 8.333317e-5 |
Frequently asked questions
How many us survey feet is 1 microinch?
How do I convert microinches to us survey feet?
How do I convert us survey feet back to microinches?
How many us survey feet is 100 microinches?
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Sources & references
Conversion factor (1 µin = 8.333317e-8 sft) 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 Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.