length · International · Modern
SI base unit of length. Its definition fixes the speed of light in vacuum at exactly 299,792,458 m/s, with the second defined from the caesium-133 hyperfine frequency.
Converter
length · Ancient Greece / Rome · Antiquity
Roman mile (mille passus)
approx.
- Record
- M137
- Definition quality
- Historically reconstructed
- Conversion mode
- multiplicative
- Calculator
- Approximately calculable
Definition
Strong internal relation; metric value follows reconstructed foot.
Reference value
One Roman mile (mille passus) is understood to be about 1,480 metres.
History & use
Strong internal relation; metric value follows reconstructed foot.
Modern use
Retained primarily for historical, educational, or reference use rather than as a current standardized calculator unit.
Did you know?
Mille passus literally means 'a thousand paces'—but the Roman passus was a double-step of five Roman feet, so the mile contained 5,000 feet.
Sources & evidence
Source tier Tier B/C — recorded secondary/reference source · confidence High
- Source 1 — https://www.cambridge.org/core/journals/britannia/article/abs/british-section-of-the-antonine-itinerary/B64AD9343A80D33DECCDB7E383807469
- Source 2 — https://www.cambridge.org/core/journals/britannia/article/abs/lengthunits-in-roman-town-planning-the-pes-monetalis-and-the-pes-drusianus/361CB63B5CDAB4A69355BBF82E04CC51
- Trivia — https://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/SMIGRA%2A/Passus.html
Related measurements
length · International · Modern
1 km = 1000 m by the SI prefix kilo-.
length · International · Modern
1 cm = 0.01 m by the SI prefix centi-.
length · International · Modern
1 mm = 0.001 m by the SI prefix milli-.
inch
inlength · UK / US · Modern / historical
1 international inch = exactly 0.0254 m.
foot
ftlength · UK / US · Modern / historical
1 international foot = exactly 0.3048 m.
yard
ydlength · UK / US · Modern / historical
1 international yard = exactly 0.9144 m.
mile
milength · UK / US · Modern / historical
1 international mile = exactly 1609.344 m = 1760 yd.