km to Miles Converter
Convert kilometers to miles for US drivers reading international road signs and race distances.
How It Works
Formula: km to mi = value × 0.621371192
Example: 100 km = 62.137119 mi
Note: 1 kilometer equals 0.6214 miles, derived from the US statute mile (1 mi = 1.609344 km).
Common Uses
Quick Conversion Table
| km | mi |
|---|---|
| 1 | 0.6214 |
| 5 | 3.1069 |
| 10 | 6.2137 |
| 50 | 31.0686 |
| 100 | 62.1371 |
| 500 | 310.6856 |
| 1000 | 621.3712 |
Rounding Rule
Rounded to 4 decimal places
Error Margin
±0.0001 mi
Precision Guidance
For driving, round to 1 decimal place. For races, keep 3 decimals.
Common Mistakes
A 5K is 3.1 miles, not 5 miles. Always convert kilometers to miles before comparing to US distances.
Frequently Asked Questions
What is 100 km in miles?
100 km equals 62.137 miles using the conversion 1 km = 0.621371 mi.
How do I convert km to miles?
Multiply the kilometer value by 0.6214, or divide by 1.6093.
What is a 5K race in miles?
A 5K race is 5 kilometers, which equals about 3.107 miles.
Is this the same as the US statute mile?
Yes, this converts to the US statute mile used on American road signs.
Deep Dive Guide
KM to Miles: Complete Conversion Guide for US Travelers
Convert km to miles with the exact 0.621371 factor. Our guide covers international road signs, races, and maps for US travelers.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 inch (in) = 25.4 millimetres (exact)
- EXACT1 foot (ft) = 0.3048 metres (exact, 12 in)
- EXACT1 yard (yd) = 0.9144 metres (exact, 3 ft)
- EXACT1 mile (mi) = 1609.344 metres (exact, 5280 ft)
- EXACT1 centimetre (cm) = 0.01 metre (definition)
Common Pitfalls & How to Avoid Them
US survey foot is deprecated
The old US survey foot (0.304800609601 m) was retired in 2023 in favor of the international foot (0.3048 m). Modern conversions use the international foot; mixing them drifts over long distances.
Inches vs. centimetres for screens
Display and wheel sizes are often rounded to the nearest convenient number; a "27-inch" monitor is nominal, not a precise 68.58 cm panel.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy