Miles to Kilometers Converter
Quick answer: One mile equals 1.609344 kilometers exactly. A marathon's 26.2 miles converts to 42.165 km.
Convert statute miles to kilometers (or kilometers back to miles) with the exact international factor. Type a value, pick a direction, and the result recalculates instantly.
Enter your distance
Your results
| Kilometers | — |
| Conversion factor | 1 mi = 1.609344 km (exact) |
How to use this calculator
Choose the conversion direction, enter your distance, and the result updates instantly. Values must be zero or positive — negative distances are rejected.
How it works
Kilometers = miles × 1.609344. Reverse: miles = kilometers ÷ 1.609344. The factor is exact by international definition.
Worked example
A marathon is 26.2 miles: 26.2 × 1.609344 = 42.1648128 → 42.165 km.
Reference data
| Unit | Equivalent |
|---|---|
| 1 mile | 1.609344 km (exact) |
| 1 km | 0.621371 mi (exact reciprocal, rounded) |
Source: international yard and pound agreement (1959) — 1 mi = 1.609344 km exactly; via NIST (2026).
Method & sources
The converter multiplies miles by 1.609344 — an exact figure, not an estimate — and divides by the same factor for the reverse direction. Because the factor is exact, displayed results are rounded only for readability; the full-precision value is computed first.
- International yard and pound agreement (1959): 1 yard = exactly 0.9144 m, so 1 mile (1,760 yards) = exactly 1,609.344 m — overview
- US metric standards and SI definitions: NIST — The SI System
Frequently asked questions
Is the conversion factor exact?
Yes — 1 mile is defined as exactly 1.609344 kilometers.
Can I convert kilometers to miles?
Yes — use the direction toggle; the tool divides by 1.609344 for the reverse conversion.
What about nautical miles?
Different unit: one nautical mile = 1.852 km exactly. This tool handles statute miles only.
Why 1.609344?
A mile is 1,760 yards and a yard is defined as exactly 0.9144 m, so 1,760 × 0.9144 = 1,609.344 m.