A marathon is 26.2 miles. How many km is this?
The correct answer and explanation is:
A marathon is 26.2 miles, which is approximately 42.1648 kilometers.
How to convert miles to kilometers
The conversion factor between miles and kilometers is:
1 mile = 1.60934 kilometers
To convert 26.2 miles to kilometers, you multiply by this factor: 26.2 miles×1.60934kmmile=42.1648 km26.2 \text{ miles} \times 1.60934 \frac{\text{km}}{\text{mile}} = 42.1648 \text{ km}
Explanation
The mile is a unit of length commonly used in the United States and the United Kingdom, while kilometers are part of the metric system, used internationally and scientifically.
Since a marathon distance is standardized internationally, the official length is exactly 42.195 kilometers, which closely matches the conversion from 26.2 miles.
The slight difference (42.195 km vs 42.1648 km) arises because the marathon distance was originally defined in miles and fractions, and the official metric equivalent was set as 42.195 km to match the course length exactly.
The conversion factor of 1 mile = 1.60934 km is very precise and widely accepted in scientific and everyday use.
Context on the marathon distance
The marathon distance of 26.2 miles (or 42.195 km) has a historic origin dating back to the 1908 London Olympics, when the race distance was extended so the race could start at Windsor Castle and finish in front of the royal box at the Olympic stadium.
This exact distance was later adopted as the official marathon length by the International Association of Athletics Federations (IAAF).
Summary
- 1 mile = 1.60934 km
- 26.2 miles × 1.60934 = 42.1648 km (approximate)
- Official marathon length = 42.195 km
Thus, a marathon is about 42.2 kilometers.