miles to km

How do you use the miles to km converter?

Type a distance in the Miles box and the Kilometers box updates as you type; the line underneath reads “10 mi = 16.093 km”. It works offline once the page has loaded and sends nothing anywhere.

1. Enter miles in the left box (it starts at 10).
2. Read km on the right, to three decimals, and in the sentence below.
3. Swap (⇄) to go from km to miles, or open the km to miles page, which leads with km and race distances.
4. Copy result puts “10 mi = 16.093 km” on your clipboard.
5. All units shows the same distance in meters, feet, yards and nautical miles.
6. The quick table lists 1 to 1,000 miles without typing.

What is the formula for miles to km?

km = miles × 1.609344. That number is exact, not measured. A mile is 5,280 feet, and since 1959 the international foot has been defined as exactly 0.3048 m, so a mile is 5,280 × 0.3048 = 1,609.344 m. NIST lists the factor in its SI guide (SP 811, Appendix B.8), and since January 1, 2023 the older US survey foot is obsolete, so every US mile, on a map or a highway, is the same 1,609.344 m.

km = miles × 1.609344  ·  miles = km × 0.621371

Miles to km conversion table (1 to 1,000 miles)

Exact conversions rounded to two decimals, with the × 1.6 shortcut alongside so you can see how far off it is. The shortcut is always 0.58% low, which is under 1 km until you pass about 107 miles.

The half and full marathon rows use the rounded mile figures runners quote; the official distances are 21.0975 km and 42.195 km, so “13.1” and “26.2” miles each fall a few dozen meters short.

How does the Fibonacci trick convert miles to km?

Take a Fibonacci number of miles and read the next Fibonacci number as km: 5 miles ≈ 8 km, 8 ≈ 13, 13 ≈ 21, 34 ≈ 55, 55 ≈ 89. It works because each Fibonacci number is about 1.618 times the one before (the golden ratio), and that is within 0.6% of 1.609 km per mile.

For numbers that are not in the sequence, split them into Fibonacci parts and add: 100 miles = 89 + 8 + 3 → 144 + 13 + 5 = 162 km (exact 160.93). 40 miles = 34 + 5 + 1 → 55 + 8 + 2 = 65 km (exact 64.37). Small numbers are rougher (3 → 5 is 3.6% high), so for short distances the × 1.6 rule is better.

Other quick methods:

• Add 60%. 45 miles: 45 + 27 = 72 km (exact 72.42).
• Double, then subtract a fifth. 50 → 100 − 20 = 80 km (exact 80.47). Same as × 1.6.
• For precision, add 1% back. × 1.6 then + 0.6% gets you within about 0.02%: 300 × 1.6 = 480, + 2.9 = 482.9 (exact 482.80).

Where do miles show up, and when do you need km?

US and UK roads, odometers and maps count miles; almost everyone else counts km. In the US, the federal Manual on Uniform Traffic Control Devices (MUTCD, Section 2H.05) has highway mileposts count miles from zero at the south and west state lines, with optional tenth-of-a-mile markers. Exit numbers on many interstates follow those mileposts, so exit 120 is about 120 miles, or 193 km, from the state line. UK signs use miles and yards too: the Highway Code traffic signs include “Road works 1 mile ahead” and motorway countdown markers of 100 yards each.

You need km when the other side does:

• Driving into Canada or Mexico. A US odometer counts miles while signs count km. If a sign says the next fuel is 80 km away, that is 49.7 miles; check your trip meter in miles against it. Our GPS odometer can show a trip in km directly.
• Speed signs at the border. Distances and speeds use the same factor. 60 mph is 96.56 km/h; for speed signs use mph to km/h.
• Running and cycling. Most race distances are metric. A 20-mile training run is 32.19 km; your pace calculator can switch between min/mile and min/km.
• Science, travel and school work. Physics problems, flight distances in many countries and most of the world’s maps are in km. A 2,500-mile coast-to-coast drive is 4,023 km.

Is 1 km half a mile? Quick size comparisons

Not quite: 1 km is 0.621 miles, a little more than half a mile, and half a mile is 0.805 km. These are the comparisons people check most often, computed exactly from 1 mile = 1.609344 km.

For walking or running times over these distances, the pace calculator turns any distance and pace into a finish time.

Statute miles vs nautical miles

A statute mile (the road mile) is 1.609344 km; a nautical mile is 1.852 km, about 15% longer. Both are exact definitions. Boats and aircraft use nautical miles because one nautical mile was originally tied to one minute of latitude. If a marine chart says 10 nmi, that is 18.52 km or 11.51 statute miles. Mixing them up adds or loses 15%. The All units panel in the converter shows nautical miles beside km and miles, and boat and plane speeds in knots are covered on knots to mph.

Common miles to km mistakes

The classic error is dividing by 1.609 instead of multiplying, which turns 10 miles into a bogus 6.2 km. The km number is always the bigger one.

• Rounding to 1.6 for long distances. Over 1,000 miles, that is 9.3 km short.
• Treating 26.2 miles as the exact marathon. It is 42.16 km; the official distance is 42.195 km.
• Reading a GPS trace as exact. Phone GPS distances can read long on twisty routes or short when the signal drops. For accuracy limits, see GPS vs car speedometer.

About this page

All conversions were computed with the site’s tested distance code (src/lib/distance.ts), using the exact NIST mile, and rounded only for display. Written by Izhar Ahmad Danish. For your live speed and trip distance, open the GPS speedometer on the homepage.