Historical Unit Converter (Leagues, Furlongs, Roman Miles, Stadia)
Convert the distance units found in historical texts (league, furlong, chain, rod, fathom, cubit, Roman mile and pace, Greek stadion, Russian verst, Chinese li) into kilometres, miles, metres or feet, and back, using the definitions published by NIST and classical reference works.
Last updated: October 2026
Converted Length
4.82803 km
Formula below · 3 sources (NIST, penelope.uchicago.edu, britannica.com) · Updated Oct 2026
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About this calculator
A league is 3 statute miles, so "twenty leagues" in an old English text is about 60 miles or 97 km; a Roman mile of 1,000 paces is about 1,480 m, a little short of the modern mile; and a Greek stadion of 600 Greek feet is about 185 m, so Herodotus's distances in stadia divide by 5.4 to give kilometres. This converter multiplies a value by the length of its unit in metres and divides by the length of the target unit, so any of the listed units can be converted into any other.
The units
The English and American survey units are defined exactly: a league is 3 miles (4,828.032 m), a furlong is 1/8 mile or 660 ft (201.168 m), Gunter's chain is 66 ft (20.1168 m), a rod, pole or perch is 16.5 ft (5.0292 m), a fathom is 6 ft (1.8288 m) and the common English cubit is 18 in (0.4572 m). NIST lists the chain, fathom, furlong, league and rod among its conversion factors. The classical units are known from surviving measuring rods, milestones and ancient authors, so they are approximate: the Roman foot (pes) was about 0.296 m, the pace (passus) five Roman feet or about 1.48 m, the Roman mile (mille passus) 1,000 paces or about 1,480 m, and the Attic stadion 600 Greek feet, about 185 m (other Greek cities used stadia from about 157 to 192 m). The Russian verst was fixed at 500 sazhen, 1,066.8 m, when Russia tied its units to the English foot in 1835. The Chinese li has been 500 m since 1929; in the Qing dynasty it was about 576 m, and earlier dynasties used values from about 415 to 560 m.
Nautical leagues
At sea a league was 3 nautical miles, 5,556 m. Columbus reckoned his distances in leagues of about 4 Roman miles, so when he wrote that his ships had sailed 30 leagues in a night he meant roughly 95 nautical miles; enter such distances as nautical leagues for a close approximation.
When the exact value is uncertain
For Roman, Greek and Chinese units, the converter uses the value most reference works give; a text from a different period or province may need a slightly different figure. For a journey, the difference between a 1,480 m and a 1,500 m Roman mile is about 1 percent, far less than the uncertainty of the ancient figure itself.
Definitions used by the converter
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| Unit | Definition | Metres | Statute miles |
|---|---|---|---|
| League (land) | 3 statute miles | 4,828.032 | 3 |
| League (nautical) | 3 nautical miles | 5,556 | 3.4523 |
| Furlong | 660 ft = 1/8 mile | 201.168 | 0.125 |
| Chain (Gunter's) | 66 ft = 100 links | 20.1168 | 0.0125 |
| Rod / pole / perch | 16.5 ft | 5.0292 | 0.003125 |
| Fathom | 6 ft | 1.8288 | 0.001136 |
| Cubit (English) | 18 in | 0.4572 | 0.000284 |
| Roman foot (pes) | surviving standards | about 0.296 | 0.000184 |
| Roman pace (passus) | 5 Roman feet | about 1.48 | 0.00092 |
| Roman mile (mille passus) | 1,000 paces | about 1,480 | 0.92 |
| Stadion (Attic) | 600 Greek feet | about 185 | 0.115 |
| Verst (Russian, from 1835) | 500 sazhen = 3,500 ft | 1,066.8 | 0.663 |
| Li (Chinese, modern) | fixed in 1929 | 500 | 0.311 |
| Li (Chinese, Qing dynasty) | 1,800 chi | about 576 | 0.358 |
How to use
Enter the number, choose the unit the text uses, and choose the unit you want. The default converts 1 league to kilometres: 1 × 4,828.032 ÷ 1,000 = 4.82803 km. For 20 Roman miles (a legion's daily march), choose Roman mile to statute mile: 20 × 1,480 ÷ 1,609.344 = 18.39 miles. For 500 stadia, choose stadion to kilometres: 500 × 185 ÷ 1,000 = 92.5 km. The tiles under the result always show the value in kilometres, statute miles and metres as well.
Frequently asked questions
How long is a league?
On land, 3 statute miles (4.83 km) in English usage; at sea, 3 nautical miles (5.56 km). The league was never a legal unit in the United States or Britain, so it varied by country and century: the French lieue was about 4 km and the Spanish legua about 4.2 to 5.6 km depending on the period.
How long was a Roman mile?
A thousand paces (mille passus) of five Roman feet each, 5,000 Roman feet in all. With a Roman foot of about 0.296 m that is about 1,480 m, or 0.92 of a statute mile; Smith's Dictionary of Greek and Roman Antiquities gives about 1,618 yards. Roman milestones mark these miles along the roads of the empire.
How long is a stadion?
Six hundred Greek feet, but the Greek foot varied by city. The Attic stadion used in Athens was about 185 m, the Olympic stadion about 192 m and the shorter Egyptian or Ptolemaic stadion about 157 m. The converter uses 185 m; multiply by 192/185 for an Olympic figure.
What is a furlong, chain and rod?
They come from English field surveying: a furlong is the length of a furrow, 660 ft (1/8 mile); Gunter's chain of 66 ft is 1/10 of a furlong, and 10 square chains make an acre; a rod (also pole or perch) is 16.5 ft, a quarter of a chain. All three are defined exactly in terms of the foot.
How long is a verst and a li?
A Russian verst is 500 sazhen or 3,500 ft, 1,066.8 m, so a verst is about two-thirds of a mile. A Chinese li is 500 m today; in the Qing dynasty (to 1912) it was about 576 m and in earlier dynasties shorter, so a distance in li from an old text should be read as roughly a third of a mile.
Why are the ancient values approximate?
Ancient units were defined by physical standards that have not survived unchanged, and the same name was used for different lengths in different places and centuries. The values here are those most reference works adopt; the real uncertainty is a few percent, which matters little for a journey but may matter for reconstructing a building.
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Sources & references
- NIST Special Publication 811, Appendix B.9 — conversion factors for length (chain, fathom, furlong, league, rod, mile, nautical mile)
- Smith, Dictionary of Greek and Roman Antiquities — Milliare (the Roman mile of 1,000 paces; LacusCurtius, University of Chicago)
- Smith, Dictionary of Greek and Roman Antiquities — Pes (the Roman and Greek foot and the stadium; LacusCurtius, University of Chicago)
- Encyclopaedia Britannica — Verst
- Encyclopaedia Britannica — Li (Chinese unit of measurement)
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