Miles to KM Converter (All Length Units)

Miles to Kilometers – Exact Factor, Formulas, Examples & FAQ

1. Core Idea

Convert miles to kilometers by multiplying miles by 1.609344. This factor is exact. Reverse: miles = kilometers ÷ 1.609344.

2. Formulas

• Forward: km = mi × 1.609344
• Reverse: mi = km ÷ 1.609344
• Approx (mental): km ≈ mi × 1.61 (over by ~0.004%)
• Approx reverse: mi ≈ km × 0.62 (slight under)

3. Quick Values (mi → km)

4. Worked Example

Example: Convert 7.3 mi to kilometers.

1. Multiply: 7.3 × 1.609344 = 11.7482112
2. Round (2 decimals for travel): 11.75 km
3. Keep more decimals for GPS logs (up to 5–6).

5. Where It's Used

Miles are used in the US & UK for road distances; kilometers are standard almost everywhere else and in science, athletics, and international transport reporting.

6. Accuracy & Tips

• 1.609344 is exact—error only comes from rounding your displayed result.
• Use 1.61 for quick estimates, then refine with exact factor.
• For calorie or pace calculations keep at least 4 decimals in intermediate steps.
• Avoid truncated reverse factor 0.621—use 0.621371 (or divide by 1.609344).

7. More Examples

8. FAQ

• How many km in a mile? 1.609344 km.
• How many miles in a km? ~0.621371 mi.
• Why not 1.61? 1.61 is a rounded convenience; exact adds precision for cumulative distances.
• Best reverse method? Divide km by 1.609344.
• When to round? Travel signage: 1 decimal; fitness: 2–3; scientific: as needed.