Free Miles to Km Converter — Exact Factor 1.609344

What is a mile, and what is a kilometer?

The mile used on roads is the statute or international mile: 5,280 feet, defined since the International Yard and Pound Agreement of 1959 as exactly 1,609.344 meters. The word comes from the Roman mille passus, a thousand paces. Miles are the unit for road distances, speed limits and race courses in the United States, and for road distances and speed limits in the United Kingdom — which is why marathon distances, road-trip plans and speedometers in both countries still speak in miles.

The kilometer is 1,000 meters — the everyday unit for road distances, race courses and speed limits (km/h) across Europe and almost everywhere else in the world. Because it is built on the meter, the kilometer is part of the International System of Units (SI). A kilometer is shorter than a mile, so the same journey always shows a bigger number in kilometers: 100 miles is 160.9344 kilometers.

How to use the converter

1. Type a distance in the Miles box — the default 26.2 is the marathon distance. The kilometers result appears instantly.
2. Or type in the Kilometers box instead: the converter works both ways, so the miles value updates at once.
3. Use the Swap button to reverse the direction. The converted value carries over as the new starting number.
4. Read the result line under the boxes: it shows the full conversion plus the one-unit rate, 1 mile = 1.60934 kilometers.

Miles to km formula

The converter uses the exact factor 1.609344, so converting there and back returns the number you started with. The common shortcut of × 1.6 is fine for a rough guess but understates the answer by about 0.6 percent — roughly 1 kilometer short on a 100-mile journey.

Worked example

A marathon is quoted as 26.2 miles. How far is that in kilometers?

Try both numbers in the converter above — and type 42.1648 in the kilometers box to watch it return 26.2 miles.

Miles to km conversion table

All values use the exact factor 1.609344 and are rounded to 4 decimal places.

Race distances and road trips, in kilometers

• One mile — 1 mile = %1*1.609344:4% kilometers.
• Parkrun — 3.1 miles = %3.1*1.609344:4% kilometers, just short of a 5K.
• 10K — 6.2 miles = %6.2*1.609344:4% kilometers, a 10K near enough.
• Half marathon — 13.1 miles = %13.1*1.609344:4% kilometers.
• Marathon — 26.2 miles = 42.1648 kilometers (official course 42.195 kilometers).
• Speed limits — 30 mph = %30*1.609344:4% km/h; 70 mph = %70*1.609344:4% km/h.
• Road trip — 250 miles = %250*1.609344:4% kilometers.

Driving abroad and unsure which unit the signs use? Our metric vs imperial conversion guide for Europe covers road signs, speed limits and fuel, country by country.

Frequently asked questions

How many kilometers is 1 mile?

One mile is exactly 1.609344 kilometers. The figure is exact: the International Yard and Pound Agreement of 1959 defined the mile as 1,609.344 meters, so multiplying by 1.609344 is never an approximation.

How many kilometers is 26.2 miles?

26.2 miles is 42.1648 kilometers (26.2 × 1.609344 = 42.1648128, rounded to 4 decimals). Note that the official marathon distance is 42.195 kilometers, which is 26 miles 385 yards — 26.2 miles is the rounded shorthand.

How do I convert miles to km in my head?

Multiply by 1.6 for a quick estimate: 50 miles × 1.6 = 80 kilometers, against the exact 80.4672 kilometers. The shortcut is within 0.6 percent, fine for journey planning. For exact figures, multiply by 1.609344.

How many km is 5 miles?

5 miles is 8.0467 kilometers (5 × 1.609344 = 8.04672, rounded to 4 decimals). A 5-mile run is therefore just over 8 kilometers.

How do I convert mph to km/h?

Multiply by 1.609344, the same factor as distance: 60 mph × 1.609344 = 96.5606 km/h. The hour is unchanged, so speed converts exactly like distance.

Why does the UK use miles but sell fuel in liters?

The United Kingdom kept miles for road distances and speed limits while adopting metric units for most other measures, including fuel sales. Road signs show miles and speed limits show mph, but petrol is sold by the liter — which is why converters between the two systems stay busy.

What is the difference between a statute mile and a nautical mile?

A statute mile — the mile in this converter — is 1.609344 kilometers and is used on roads. A nautical mile is 1.852 kilometers exactly and is used in sea and air navigation. The two differ by about 15 percent, so never swap them.

Sources

• NIST Special Publication 811, Guide for the Use of the International System of Units (SI) — nist.gov/pml/special-publication-811
• BIPM, The International System of Units (SI Brochure) — bipm.org
• International Yard and Pound Agreement, 1959 — the foot fixed at exactly 0.3048 meters and the international mile at exactly 1.609344 kilometers.

Conversion factors checked against these sources on 14 November 2026.

Disclaimer: conversions multiply by the exact factor 1.609344; always follow the speed limit shown on local road signs.

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