A miles to kilometers calculator converts a US/UK distance to its metric equivalent using the exact factor 1 mile = 1.609344 km. Enter the value in miles and the calculator returns the kilometer equivalent.
Useful for international travelers reading European or Asian road signs, runners comparing race distances (5K, 10K, marathon = 26.2 mi / 42.2 km), car shoppers translating MPG to liters-per-100-km, and anyone reading distance figures across the metric/customary divide.
Key takeaway
A mile is roughly 1.6 kilometers, with the precise factor being 1.609344. The metric world uses km as the standard road and travel unit; the US, UK, and a few small territories still use miles. The conversion is exact by international agreement, but for mental math the rough "1.6×" multiplier is within 0.6%, easily good enough for everyday use.
How it's calculated
The conversion:
kilometers = miles × 1.609344
The 1.609344 factor is exact, defined by the international yard and pound agreement of 1959, which standardized the mile at exactly 1,760 yards × 0.9144 m/yard = 1,609.344 m. Before then, slightly different "miles" existed (US survey mile, Roman mile, nautical mile = 1.852 km), but the statute mile at 1.609 km is what every English-speaking country uses for road distances today.
For air and sea navigation, the nautical mile (1.852 km) is the standard, it's defined as one minute of arc along a meridian, so it has natural geographic meaning. Aviation speeds and distances are typically nautical, not statute.
Source: NIST exact conversion, 1 mile = 1.609344 km
Examples
10 miles, typical commute
- Distance 10 mi
10 miles converts to 16.09 km. The typical US one-way commute is about 13-15 miles (~21-24 km); European commutes average a bit shorter, around 10-12 km / 6-7 mi. Mental check: 10 × 1.6 = 16 km (within 0.6% of actual).
26.2 miles, marathon distance
- Distance 26.2 mi
A marathon's 26.2 miles is 42.16 km. The standard distance was set at the 1908 London Olympics (originally an uneven 26 miles 385 yards, chosen to align with Windsor Castle's start line and the royal box at the finish). Modern races worldwide reference both figures; metric runners think in km splits.
Frequently asked questions
How do I convert miles to kilometers in my head?
Multiply by 1.6 for a quick estimate within 0.6% of the exact answer. For more accuracy, add 60% to the mile figure (which is identical math). So 25 miles × 1.6 = 40 km (actual: 40.2). The shortcut is good across any distance, there's no drift like there is with the temperature shortcuts.
Why is the factor 1.609344?
It comes from the international definitions of the yard (exactly 0.9144 m) and the mile (exactly 1,760 yards). 1,760 × 0.9144 = 1,609.344 m = 1.609344 km, exactly. The factor has been standardized since 1959; before that, the US and UK had slightly different national values for the yard, which produced miles that differed at the part-per-million level.
What's the difference between a statute mile and a nautical mile?
A statute mile (the everyday US road mile) = 1.609344 km. A nautical mile = 1.852 km, defined as one minute of latitude. Aviation and maritime distances use nautical miles because they have natural geographic meaning (you can read distance off a chart by counting minutes of arc). Cars and roads use statute miles everywhere mile-based.
How does mph translate to km/h?
Multiply mph by 1.609344 (or roughly 1.6), the same factor as the distance conversion, since speed is just distance per unit time and the time unit doesn't change. So 60 mph ≈ 96.6 km/h, 70 mph ≈ 112.7 km/h, 80 mph ≈ 128.7 km/h. Most European motorways post 130 km/h limits ≈ 80 mph; UK motorways post 70 mph ≈ 113 km/h.