How this instrument works
These two units were born of opposite impulses. Metres came out of revolutionary France in 1791, defined as one ten-millionth of the quadrant running from pole to equator along the meridian through Paris, then redefined twice more: by krypton-86 wavelengths in 1960, and in 1983 by fixing light's speed at 299 792 458 m/s. Statute miles are older and far less tidy — Rome's mille passuum, one thousand double paces of a marching legion, which Elizabethan legislation of 1593 stretched to 5280 feet so it would swallow eight of the furlongs already ploughed into English fields.
So this factor is decreed rather than measured. Under the 1959 international yard and pound agreement, six national laboratories pinned one yard to 0.9144 m, and 1760 of those yards make one statute mile of 1609.344 m to its final digit. Invert that and one metre becomes 125⁄201168 mile. Since 201168 factors as 2⁴ × 3² × 11 × 127, carrying primes other than 2 and 5, its decimal expansion cannot terminate: it runs 0.00062137119223733397… without end, so every printed multiplier is merely a snipped copy of an exact fraction.
Both units stay in daily service, often within sight of each other. Road signs across America, Britain, Liberia and Myanmar count miles while surveyors, engineers and pharmacists in those same countries work metric; British motorways post junction distances in miles and bridge clearances in metres. Athletics splits things by convention — one lap is 400 m, a 5K start line is metric, yet runners narrate their training in miles and nickname 1500 m 'the metric mile' though it falls 6.8% short of one.
- Type your distance into Metres (m). That field opens at 1000, one kilometre, as a reference point.
- Read the answer on the Miles (mi) line; it recomputes on every keystroke, with no button to press.
- Working backwards from mileage? Multiply your figure by 1609.344 and type that result into Metres (m).
- Trim to three decimals for road, trail or race use. Keep the long tail only if this feeds another calculation.
Worked example — one 1000 m loop, told in miles
One race director chalks out a flat 1000 m loop through her local park and wants mile flags on it. Typing 1000 into Metres (m) returns 0.621371192237 on the Miles (mi) line, so eight laps come to 4.970969537896 mi and that first mile flag belongs 609.344 m into lap two.
One number, several familiar shorthands. Ten of those loops give 6.21371192237 mi, which is where '10K is 6.2 miles' comes from; 42195 m reads 26.218757 mi, just over 26 miles 385 yards — that odd racing distance settled at London's 1908 Games works out to 42194.988 m precisely.
Questions
Is the mile exactly 1609.344 metres?
Yes — that figure is legislated, not surveyed. Signatories to the 1959 international yard and pound agreement set one yard equal to 0.9144 m; take 1760 of them and a statute mile lands on 1609.344 m carrying no uncertainty whatsoever. Every digit of this converter's multiplier descends from that single clause, so the only error you can meet here is whatever rounding you choose at the end.
Why does the multiplier carry fifteen digits?
Because its true value never ends. One metre is 125⁄201168 mile, and 201168 = 2⁴ × 3² × 11 × 127 holds prime factors beyond 2 and 5, so the expansion repeats instead of stopping: 0.00062137119223733397… Cutting it at 0.000621371192237 leaves results low by roughly 5 parts in 10 000 000 000 000 — half of one nanometre for every kilometre you enter, well past anything a tape, measuring wheel or GPS receiver could ever resolve.
Are these statute miles or nautical miles?
Statute miles — the land mile of 5280 feet. Nautical miles are wholly separate, exactly 1852 m, agreed at Monaco's hydrographic conference in 1929 because that length sits close to one minute of latitude, and they run 15.08% longer. If your figure came off charts, flight plans or ships' logs, divide by 1852 instead; this page's factor would overstate every leg you plotted.
How many miles is 100 m, or 5 km?
100 m is 0.0621371192237 mi, just under one-sixteenth, and 5000 m is 3.106855961185 mi — hence '5K is 3.1 miles'. Each 400 m lap works out to 0.2485 mi, so four laps fall 9.344 m short of a full mile. That gap is exactly why mile races on standard outdoor tracks begin 9.344 m behind their common start line.
Does the retired US survey mile give a different answer?
Slightly, and you should no longer use it. That mile rested on the US survey foot of 1200⁄3937 m, making it 1609.347219 m — some 3.2 mm longer than the international mile applied here. NIST and NOAA withdrew the survey foot at the close of 2022. Its two-parts-per-million gap only ever showed up in state plane coordinate grids, where coordinates run into hundreds of kilometres and those millionths add into real metres.
Can I just multiply by 0.00062 in my head?
For a rough head count, yes, but know how far it slips. Truncating to 0.00062 runs about 0.22% low, which throws away 93 m across a marathon course — enough to misplace one checkpoint. Cruder still, 0.0006 sits 3.4% low and turns your 10K into 6.0 miles flat. Rounding at the finish rather than at the start costs nothing: enter the full metre figure, then trim your mileage to whatever map, sign or certificate actually calls for.