Conversions
13 calculators
Unit converters for the numbers that come out of training: weights, distances, speeds, paces, energy, temperature and the equipment-specific units that only make sense inside one sport. Each one applies an exact defined factor rather than a rounded approximation.
The factors matter more than they look. One international mile is exactly 1.609344 kilometres and one pound is exactly 0.45359237 kilograms, both by definition rather than by measurement. Rounding those to 1.6 and 0.45 is where most hand conversions start to disagree with each other.
- Distance Converter (km to miles) Convert distances between kilometres and miles using the internationally standardised conversion factor.
- Height Converter (cm to feet/inches) Convert height between centimetres and feet/inches using the international standard conversion factor.
- Pace Converter (Multiple Units) Convert running pace between min/km, min/mi, mph, and km/h using standard distance ratios.
- Weight Converter (kg to lbs) Convert weight between kilograms and pounds using the internationally defined conversion factor.
- Energy Converter (kcal to kJ) Convert energy values between kilocalories (kcal) and kilojoules (kJ) using the standard 4.184 factor.
- Grade to Degrees Converter Convert incline between percent grade and degrees, with rise-over-run shown both ways.
- Hydration Volume Converter (L to fl oz) Convert between litres and US fluid ounces for hydration and beverage volumes.
- Plate Weight Converter (kg to lb plates) Convert kilogram barbell targets to the nearest standard-plate combination in pounds per side.
- Rowing Split to Watts Converter Convert a 500 m rowing split into watts, calories per hour, and mechanical work using Concept2's published relations.
- Speed Converter (MPH to km/h to m/s) Convert running and cycling speeds between mph, km/h, and m/s using international standard factors.
- Watts to METs Converter Convert cycling power output into METs and oxygen uptake using the ACSM leg-ergometry equation.
- Resistance Band Weight Equivalent Converter Convert resistance band stretch percentage to free-weight equivalent tension.
- Sauna Temperature Converter Convert sauna temperatures between Celsius and Fahrenheit using the standard thermodynamic formulas.
Why an exact factor changes the answer
A conversion error compounds with the size of the number it is applied to. Converting a 5 km run with a factor of 1.6 instead of 1.609344 loses about 29 metres, which nobody notices. Applying the same rounding across a marathon shifts the distance by about 245 metres, and applying it to a pace shifts a projected finish time by well over a minute.
Pace conversions carry a second trap: pace is time per distance, so it scales opposite to a distance. A mile takes longer to cover than a kilometre, so a 5:00 min/km pace becomes 8:03 min/mile — the number goes up where a distance conversion would send it down.
The sport-specific converters
Several units here exist only inside one discipline. A rowing split is time per 500 m, which converts to speed through a cube relationship with power rather than a linear one. Watts convert to METs through the ACSM leg ergometry equation, where oxygen uptake is 1.8 × 6.12 × watts ÷ body mass + 7, then divided by 3.5 to reach METs.
Grade converts between percent and degrees through the arctangent, which is why a 100% grade is 45 degrees rather than 90 — a distinction that matters on any treadmill or hill-climbing calculation. Plate and band converters translate between the equipment marked in one system and a session planned in the other.
Common questions
How many kilometres are in a mile?
Exactly 1.609344 kilometres. That figure is a definition rather than a measurement: the international yard and pound agreement of 1959 fixed the yard at exactly 0.9144 metres, which makes the mile exactly 1609.344 metres. Every distance, speed and pace converter on this page carries the full factor rather than a rounded 1.61 or 1.6, and rounds only once when the figure reaches the screen.
Why does converting a pace not work like converting a distance?
Pace is time divided by distance, so it is the reciprocal of speed and scales in the opposite direction. Converting 10 km to miles divides by 1.609344 and gives a smaller number, 6.21. Converting 5:00 min/km to min/mile multiplies by the same factor and gives a larger one, 8:03, because a mile takes longer to cover than a kilometre. Applying the wrong direction is the commonest error in hand-converted paces.
Is 1 kg exactly 2.2 lbs?
No, and the gap matters at barbell weights. One pound is defined as exactly 0.45359237 kg, which makes one kilogram 2.2046226 lbs. Using 2.2 understates a 100 kg lift by about 0.46 lbs, and the error grows with the load. The weight converter here carries the full factor, which is also why converted plate loadings sometimes land on a figure that no plate set can actually make.