Convert Microinch to Perch
Convert microinches to perches instantly. 1 microinch = 5.050505e-9 perch — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Perch 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.
Perch
A perch is an Imperial unit of length identical to the rod — 16.5 feet (about 5.03 m). The names 'rod', 'perch', and 'pole' all refer to the same surveying unit and differ only by regional preference.
Like the rod, the perch derives from medieval English land-surveying. The name 'perch' was particularly common in legal land descriptions in Ireland and parts of the UK.
Perches appear in legacy land descriptions in Ireland, the UK, and historical US documents. Modern usage is rare.
Medieval English surveying origin; identical to the rod since 1620; became exact via the 1959 International Yard and Pound Agreement.
Microinch to Perch conversion formula
The relationship between microinches and perches:
To convert microinches to perches, multiply the value in microinches by 5.050505e-9. To reverse, multiply perches by 1.98e+8.
How to use this converter
Type a value into the calculator. The result in perches updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Perch to Microinch converter for the reverse direction.
Step-by-step: convert microinches to perches
- Write down the value in microinches (µin).
- Multiply that value by the factor 5.050505e-9.
- The product is the equivalent value in perches (perch).
- To reverse, multiply the perch value by 1.98e+8.
Worked examples
Example 1 — Convert 1 µin to perch:
1 × 5.050505e-9 = 5.050505e-9 perch
Example 2 — Convert 100 µin to perch:
100 × 5.050505e-9 = 5.050505e-7 perch
Real-world example — From sub-micron to human scale
One billion microinches equals one perch — the conversion that drives home the gulf between atomic-scale features and everyday objects in physics curricula.
1e+9 µin × 5.050505e-9 = 5.0505050505 perch
Real-world example — Bridging nine orders of magnitude
500 million microinches equals a value comfortably in the human-scale perches 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 × 5.050505e-9 = 2.5252525253 perch
Microinch to Perch conversion table
Standard reference values for converting microinches to perches:
| Microinch [µin] | Perch [perch] |
|---|---|
| 0.01 | 5.050505e-11 |
| 0.1 | 5.050505e-10 |
| 1 | 5.050505e-9 |
| 2 | 1.010101e-8 |
| 3 | 1.515152e-8 |
| 4 | 2.020202e-8 |
| 5 | 2.525253e-8 |
| 10 | 5.050505e-8 |
| 20 | 1.010101e-7 |
| 30 | 1.515152e-7 |
| 40 | 2.020202e-7 |
| 50 | 2.525253e-7 |
| 100 | 5.050505e-7 |
| 500 | 2.525253e-6 |
| 1000 | 5.050505e-6 |
Frequently asked questions
How many perches is 1 microinch?
How do I convert microinches to perches?
How do I convert perches back to microinches?
How many perches is 100 microinches?
Popular length unit conversions
Convert Microinch to other length units
Show all Microinch conversions
Metric / SI (4 units)
Imperial / US Customary (26 units)
Sources & references
Conversion factor (1 µin = 5.050505e-9 perch) 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.