Convert Mil to Perch
Convert mils to perches instantly. 1 mil = 5.050505e-6 perch — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Perch to Mil converter for the reverse conversion.
Units explained
Mil
A mil (also called a thou) is an Imperial unit of length equal to one thousandth of an inch (1/1000 in = 0.0254 mm = 25.4 μm exactly). It is used in engineering, manufacturing, and materials specifications.
The mil is derived from the Latin mille, "thousand," denoting one-thousandth of an inch. Standardized in industrial use during the 19th-century rise of precision engineering.
Mils are used to specify thicknesses of plastic films, foils, paper, copper traces on printed circuit boards (PCBs), wire insulation, and paint coatings. A standard sheet of paper is about 4 mils thick.
Adopted in 19th-century engineering practice; the value (1/1000 in) became exact in 1959 when the inch was fixed at 25.4 mm via the International Yard and Pound Agreement. The British term is "thou"; American term is "mil".
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.
Mil to Perch conversion formula
The relationship between mils and perches:
To convert mils to perches, multiply the value in mils by 5.050505e-6. To reverse, multiply perches by 198000.
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 Mil converter for the reverse direction.
Step-by-step: convert mils to perches
- Write down the value in mils (mil).
- Multiply that value by the factor 5.050505e-6.
- The product is the equivalent value in perches (perch).
- To reverse, multiply the perch value by 198000.
Worked examples
Example 1 — Convert 1 mil to perch:
1 × 5.050505e-6 = 5.050505e-6 perch
Example 2 — Convert 100 mil to perch:
100 × 5.050505e-6 = 0.0005050505 perch
Real-world example — Macro-scale buildup
A million mils equals exactly one perch — the conversion that bridges microscale features and macroscale objects in microfluidic, biomedical, and semiconductor packaging design.
1000000 mil × 5.050505e-6 = 5.0505050505 perch
Real-world example — Quarter-meter measurement reference
A 250,000-mil length equals 0.25 perches — useful for comparing supply-chain spec sheets where some lengths are quoted in the smaller unit and some in the larger.
250000 mil × 5.050505e-6 = 1.2626262626 perch
Real-world example — From microscopic to macroscopic
A million mils equals exactly one perch. This kind of conversion appears in microfluidics, where total channel length is given in perches but feature widths are in mils.
1000000 mil × 5.050505e-6 = 5.0505050505 perch
Mil to Perch conversion table
Standard reference values for converting mils to perches:
| Mil [mil] | Perch [perch] |
|---|---|
| 0.01 | 5.050505e-8 |
| 0.1 | 5.050505e-7 |
| 1 | 5.050505e-6 |
| 2 | 1.010101e-5 |
| 3 | 1.515152e-5 |
| 4 | 2.020202e-5 |
| 5 | 2.525253e-5 |
| 10 | 5.050505e-5 |
| 20 | 0.0001010101 |
| 30 | 0.0001515152 |
| 40 | 0.0002020202 |
| 50 | 0.0002525253 |
| 100 | 0.0005050505 |
| 500 | 0.0025252525 |
| 1000 | 0.0050505051 |
Frequently asked questions
How many perches is 1 mil?
How do I convert mils to perches?
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How many perches is 100 mils?
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Metric / SI (7 units)
Imperial / US Customary (26 units)
Nautical (1 units)
Sources & references
Conversion factor (1 mil = 5.050505e-6 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 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.