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Kilometers to Miles (km to mi)
Convert kilometers to miles instantly. The formula is miles = km ÷ 1.609344 — divide kilometers by 1.609344 — or use the runner's shortcut: miles ≈ km × 0.62. Everything is computed locally in your browser; nothing is uploaded.
How to convert km to mi
The exact conversion factor between kilometers and miles gives the formula miles = km ÷ 1.609344. Divide kilometers by 1.609344 — or use the runner's shortcut: miles ≈ km × 0.62.
For a rough mental estimate, remember that 1 km = 0.6214 mi. To go the other way, see the miles to kilometers converter — it uses the reciprocal factor.
Worked examples
Example: convert 5 km to mi. Apply the formula — miles = km ÷ 1.609344 — and you get 3.11 mi. Reverse-check it by using the miles to kilometers to come back to 5 km; if you do not land on the original number, a factor was inverted.
Example: convert 100 km to mi. Apply the formula — miles = km ÷ 1.609344 — and you get 62.14 mi. Reverse-check it by using the miles to kilometers to come back to 100 km; if you do not land on the original number, a factor was inverted.
Where the factor comes from
The modern factors date to the international yard and pound agreement of 1959, in which the United States, the United Kingdom, Canada, Australia, New Zealand and South Africa agreed that one yard equals exactly 0.9144 meters. That single definition pins down every length factor on this page: the inch is exactly 2.54 cm, the foot exactly 0.3048 m, and the mile exactly 1,609.344 m. Before 1959, national standards differed by parts per million — irrelevant for a recipe, but critical for surveying and engineering, which is why the agreement exists.Common mistakes
Reusing the factor backwards. 1 inch = 2.54 cm does not mean 1 cm = 2.54 in. The reverse factor is 0.3937. If a result looks too large by roughly 6.5×, you inverted the factor.
Rounding mid-calculation. Converting meters → feet → inches in two steps rounds twice. Convert directly to the smallest unit you need, then round once at the end.
Mixing up US survey units. The US survey mile (used in old land records) differs from the international mile by about 2 ppm. For anything except geodetic work, the international factor on this page is correct.
Quick mental shortcuts
Mental shortcuts: cm → in ≈ divide by 2.5 (then subtract 4%); in → cm ≈ ×2.5 (then add 4%); km → mi ≈ ×0.6 (a marathon, 42.195 km, is 26.2 mi); m → ft ≈ ×3.3 (a 2 m door is about 6.6 ft).
Common km to mi conversions
| Kilometer (km) | Mile (mi) |
|---|---|
| 1 | 0.6214 |
| 5 | 3.11 |
| 10 | 6.21 |
| 42.195 | 26.22 |
| 100 | 62.14 |
FAQ
How do I convert km to mi?
miles = km ÷ 1.609344. Divide kilometers by 1.609344 — or use the runner's shortcut: miles ≈ km × 0.62.
What is 5 km in mi?
5 km equals 3.11 mi. Use the converter above for any value.
How do I convert mi back to km?
Use the reverse conversion — see our miles to kilometers converter. The calculator above also shows the reciprocal rate.
Is the km-to-mi conversion exact?
Yes — modern units are defined by international agreement with exact factors (e.g. 1 inch = 2.54 cm exactly). Results are rounded only for display.
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