Convert Mil to US Survey Foot
Convert mils to us survey feet instantly. 1 mil = 8.333317e-5 us survey foot — use the live calculator, the exact formula, a conversion table and worked examples. Also check the US Survey Foot 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".
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.
Mil 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 mils and us survey feet:
To convert mils to us survey feet, multiply the value in mils by 8.333317e-5. To reverse, multiply us survey feet by 12000.024000048.
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 Mil converter for the reverse direction.
Step-by-step: convert mils to us survey feet
- Write down the value in mils (mil).
- Multiply that value by the factor 8.333317e-5.
- The product is the equivalent value in us survey feet (sft).
- To reverse, multiply the us survey foot value by 12000.024000048.
Worked examples
Example 1 — Convert 1 mil to sft:
1 × 8.333317e-5 = 8.333317e-5 sft
Example 2 — Convert 100 mil to sft:
100 × 8.333317e-5 = 0.0083333167 sft
Real-world example — From microscopic to macroscopic
A million mils equals exactly one us survey foot. This kind of conversion appears in microfluidics, where total channel length is given in us survey feet but feature widths are in mils.
1000000 mil × 8.333317e-5 = 83.3331666667 sft
Real-world example — Macro-scale buildup
A million mils equals exactly one us survey foot — the conversion that bridges microscale features and macroscale objects in microfluidic, biomedical, and semiconductor packaging design.
1000000 mil × 8.333317e-5 = 83.3331666667 sft
Real-world example — Quarter-meter measurement reference
A 250,000-mil length equals 0.25 us survey feet — useful for comparing supply-chain spec sheets where some lengths are quoted in the smaller unit and some in the larger.
250000 mil × 8.333317e-5 = 20.8332916667 sft
Mil to US Survey Foot conversion table
Standard reference values for converting mils to us survey feet:
| Mil [mil] | US Survey Foot [sft] |
|---|---|
| 0.01 | 8.333317e-7 |
| 0.1 | 8.333317e-6 |
| 1 | 8.333317e-5 |
| 2 | 0.0001666663 |
| 3 | 0.0002499995 |
| 4 | 0.0003333327 |
| 5 | 0.0004166658 |
| 10 | 0.0008333317 |
| 20 | 0.0016666633 |
| 30 | 0.002499995 |
| 40 | 0.0033333267 |
| 50 | 0.0041666583 |
| 100 | 0.0083333167 |
| 500 | 0.0416665833 |
| 1000 | 0.0833331667 |
Frequently asked questions
How many us survey feet is 1 mil?
How do I convert mils to us survey feet?
How do I convert us survey feet back to mils?
How many us survey feet is 100 mils?
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Sources & references
Conversion factor (1 mil = 8.333317e-5 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 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.