Sports unit conversion reference
One page for the conversions you actually reach for in running, swimming and lifting — miles to kilometres, pounds to kilograms, pace to speed and temperature. Every factor below is the exact, internationally defined value, so you can use it for records as well as everyday back-of-the-envelope maths.
Open the Running Pace calculatorBookmark this page and skip the guesswork. The tables below give the conversions used most in endurance and strength sports, starting with the ones defined exactly in the International System of Units (SI). Where a value is rounded, it is marked as approximate.
Distance and length
| From | To | Factor / value |
|---|---|---|
| 1 mile | kilometres | 1.609344 km (exact) |
| 1 yard | metres | 0.9144 m (exact) |
| 25 yards | metres | 22.86 m |
| 100 yards | metres | ≈ 91.44 m |
| 5K | — | 5 km (3.10686 mi) |
| 10K | — | 10 km (6.21371 mi) |
| Half marathon | — | 21.0975 km (13.1094 mi) |
| Marathon | — | 42.195 km (26.2188 mi) |
The mile and yard are both defined in terms of the metre, so those two rows are not measurements — they are exact by international agreement. Standard road distances such as the half and full marathon are fixed by World Athletics.
Mass and weight
| From | To | Factor / value |
|---|---|---|
| 1 pound (lb) | kilograms | 0.45359237 kg (exact) |
| 1 kilogram | pounds | ≈ 2.2046226 lb |
The international avoirdupois pound is defined as exactly 0.45359237 kg. The reverse factor (2.2046226 lb per kg) is that value inverted and rounded — close enough for plate maths, but use the exact pound-to-kg factor when a record depends on it.
Pace and speed
| Convert | Method |
|---|---|
| min/km → min/mile | × 1.609344 |
| min/mile → min/km | ÷ 1.609344 |
| pace (min/km) → speed (km/h) | 60 ÷ pace |
| km/h → mph | × 0.621371 |
| mph → km/h | ÷ 0.621371 |
Pace and speed are reciprocals: a pace in minutes per kilometre becomes a speed in kilometres per hour by dividing into 60. So 6:00/km (6 minutes) is 60 ÷ 6 = 10 km/h. The running pace calculator does all of these live if you would rather type a time and distance.
Temperature
Useful for race-day conditions and pool temperatures. To reverse it, subtract 32 first, then
multiply by 5/9: °C = (°F − 32) × 5/9. For example, 20 °C is
20 × 9/5 + 32 = 68 °F.
Swimming pool courses are not unit conversions
A common mistake is to treat swimming courses as if you could convert between them with a factor. You cannot. Short-course metres (SCM, 25 m), long-course metres (LCM, 50 m) and short-course yards (SCY, 25 yd) differ by the pool length, which changes the number of turns and push-offs. Times are therefore not directly comparable across courses even after converting yards to metres. See SCM, LCM and SCY course differences for how the standards handle this.
Worked conversions
- 5:00/km to min/mile. 5:00 is 5 minutes. 5 × 1.609344 = 8.0467 minutes. 0.0467 × 60 ≈ 2.8 seconds, so about 8:03 per mile.
- 80 kg to pounds. 80 × 2.2046226 = 176.37 ≈ 176.4 lb.
- 10 mile race in km. 10 × 1.609344 = 16.09 km.
Factors marked exact (1 mile = 1.609344 km, 1 yard = 0.9144 m, 1 lb = 0.45359237 kg) are definitions and can be used for record-grade calculations. Reverse factors such as 2.2046226 lb/kg or 0.621371 for km/h to mph are rounded — fine for everyday use, but round only at the final step when accuracy matters.
Which factor should I use?
For anything official — a ratified record, a qualifying time, a published result — use the exact defining factor and carry full precision through the calculation, rounding once at the end. For training logs, warm-up maths and pacing on the run, the rounded factors are more than accurate enough: 1.61 for miles and 2.2 for pounds will not move a training decision.
Frequently asked questions
How do I convert min/km to min/mile?
Multiply your pace in minutes per kilometre by 1.609344 to get minutes per mile. To go the other way, divide the min/mile pace by 1.609344. For example, 5:00/km is 5 × 1.609344 = 8.05 minutes, which is about 8:03 per mile.
How many kilograms is one pound?
Exactly 0.45359237 kg by international definition. Going the other way, one kilogram is about 2.2046226 pounds, so 80 kg is roughly 176.4 lb.
Can I compare swimming times across pool courses?
Not directly. Short-course metres (25 m), long-course metres (50 m) and short-course yards (25 yd) produce systematically different times because of the number of turns and the wall distance, so they are not simple unit conversions of each other.
Related tools and reading
Running Pace calculator
Type a time and distance to get pace in min/km and min/mile, plus speed — all conversions handled.
ToolRowing Split calculator
Convert between 500 m splits, distance and pace on the erg without doing the arithmetic by hand.
Sources
- BIPM & NIST, SI unit conversion factors — exact definitions of the international mile (1.609344 km), yard (0.9144 m) and avoirdupois pound (0.45359237 kg). Checked 24 Aug 2026.
- World Athletics, Competition and Technical Rules — standard road race distances, including the half marathon (21.0975 km) and marathon (42.195 km). Checked 24 Aug 2026.