Convert Furlong to US Survey Foot
Convert furlongs to us survey feet instantly. 1 furlong = 659.99868 us survey foot — use the live calculator, the exact formula, a conversion table and worked examples. Also check the US Survey Foot to Furlong converter for the reverse conversion.
Units explained
Furlong
A furlong is an Imperial unit of length equal to 660 feet, or exactly one eighth of a mile (about 201.17 m). It is the longest unit in the traditional English farm-and-survey system.
The furlong derives from Old English furh (furrow) + lang (long) — originally the length of a furrow in a typical medieval English open field. Standardised at 660 feet (= 10 chains = 220 yards = 1/8 mile) in medieval times.
Furlongs are the standard distance unit in horse racing (e.g., 'The race is 8 furlongs'), historical English farming and surveying, and occasional poetic or rhetorical usage. Modern racing courses worldwide list distances in furlongs.
Medieval English farming origin; standardised at 660 feet; remains the official distance unit in flat-racing thoroughbred horse races worldwide.
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.
Furlong 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 furlongs and us survey feet:
To convert furlongs to us survey feet, multiply the value in furlongs by 659.99868. To reverse, multiply us survey feet by 0.0015151545.
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 Furlong converter for the reverse direction.
Step-by-step: convert furlongs to us survey feet
- Write down the value in furlongs (fur).
- Multiply that value by the factor 659.99868.
- The product is the equivalent value in us survey feet (sft).
- To reverse, multiply the us survey foot value by 0.0015151545.
Worked examples
Example 1 — Convert 1 fur to sft:
1 × 659.99868 = 659.99868 sft
Example 2 — Convert 100 fur to sft:
100 × 659.99868 = 65999.868 sft
Furlong to US Survey Foot conversion table
Standard reference values for converting furlongs to us survey feet:
| Furlong [fur] | US Survey Foot [sft] |
|---|---|
| 0.01 | 6.5999868 |
| 0.1 | 65.999868 |
| 1 | 659.99868 |
| 2 | 1319.99736 |
| 3 | 1979.99604 |
| 4 | 2639.99472 |
| 5 | 3299.9934 |
| 10 | 6599.9868 |
| 20 | 13199.9736 |
| 30 | 19799.9604 |
| 40 | 26399.9472 |
| 50 | 32999.934 |
| 100 | 65999.868 |
| 500 | 329999.34 |
| 1000 | 659998.6799999999 |
Frequently asked questions
How many us survey feet is 1 furlong?
How do I convert furlongs to us survey feet?
How do I convert us survey feet back to furlongs?
How many us survey feet is 100 furlongs?
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Sources & references
Conversion factor (1 fur = 659.99868 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.