Unit Converter
I built this for quick conversions between common fitness and nutrition units. Enter a value on either side.
Quick reference
Learn the details
How it's figured
Converts common fitness and nutrition units with standard factors: pounds to kilograms (÷ 2.2046), inches to centimeters (× 2.54), miles to kilometers (× 1.609344), kilocalories to kilojoules (× 4.184), a US teaspoon to 4.93 milliliters with 3 to the tablespoon and 16 tablespoons to the cup, and Fahrenheit to Celsius ((°F − 32) × 5/9). Pace is 60 divided by speed, in minutes per kilometer or mile.
Worth memorizing: 1 kg ≈ 2.2 lbs, 1 inch = 2.54 cm, 1 mile ≈ 1.6 km, 1 kcal ≈ 4.2 kJ. This tool handles the rest when you need exact values.
Why it's an estimate
Most conversions here are exact by definition rather than approximate, which matters more than it sounds: it means the only error is the one you introduce by rounding. Here is where that rounding shows up, and the gym maths it quietly breaks.
Which factors are exact
A pound is defined as exactly 0.45359237 kilograms, an inch as exactly 2.54 centimeters, and a mile as exactly 1.609344 kilometers. These are not measurements anybody is still refining, they are definitions agreed in 1959, so a conversion between them is exact and this tool uses the full factors rather than the shortened ones. Temperature is the odd one out because the two scales do not share a zero: Celsius is Fahrenheit minus 32, times 5/9. That subtraction is why you cannot convert a temperature difference the same way you convert a temperature.
A worked example
Take a 100 kilogram squat. Divide by 0.45359237 and you get 220.46 pounds. Now take what looks like the same lift in a pound gym, 225 pounds, and convert the other way: 225 times 0.45359237 is 102.06 kilograms. Those are not the same lift, they are about 4.5 pounds apart, which is a whole small plate. Height works the same way. Six foot two is 74 inches, times 2.54 is 187.96 centimeters, which is why you see both 188 and 187 written down for the same person depending on who rounded first.
Where rounding actually bites
The everyday shortcut, 1 kilogram is 2.2 pounds, is off by about a fifth of a percent. On a single bodyweight reading that is nothing: 180 pounds is 81.6 kilograms done properly and 81.8 with the shortcut, a gap no bathroom scale would show you. It starts to matter when the number is large or when you convert repeatedly, because each pass keeps the error and adds its own. Converting a 405 pound deadlift with 2.2 lands you 4 tenths of a kilogram away from the real 183.7, and a number that has been rounded to the nearest kilogram, converted to pounds, and rounded again is no longer the number you started with. Convert once, from whatever you actually measured, and keep the original.
Bars and plates do not convert
This is the one that catches people moving between gyms. A standard Olympic barbell is 20 kilograms, which is 44.09 pounds, but American gyms sell a 45 pound bar, which is 20.41 kilograms. The plates differ the same way: a 20 kilogram plate is 44.09 pounds and a 45 pound plate is 20.41 kilograms. So the loads themselves do not line up, and a program written in kilos cannot be run by swapping each number for its nearest pound plate. What travels between gyms is the percentage, not the plate. Work out the percentage of your max the session calls for, then load whatever the bar in front of you can actually make.
Pace, which converts backwards
Running pace is minutes per distance, so the distance is on the bottom and the conversion runs the opposite way to everything above. A longer unit means a bigger number, not a smaller one. An 8 minute mile is a 4 minute 58 second kilometer, and a 5 minute kilometer is an 8 minute 3 second mile. Speed behaves normally, since 6 miles per hour really is 9.66 kilometers per hour, which is why it is easier to sanity check a pace by converting the speed instead.
What the number is usually for
Most people land here on the way to something else, and the something else is normally a bodyweight going into a calculation. If that is you, your weight in either unit is the input for your maintenance calories, which is the number most nutrition decisions get made against, and for a daily protein target. Both take pounds or kilograms, so you do not have to convert first.
Questions people ask
- 01How do I convert kg to lbs?
- Multiply the kilograms by 2.2046. So 70 kg is about 154 lbs. Going the other way, divide the pounds by 2.2046. For gym maths, 1 kg is close enough to 2.2 lbs that you can do it in your head.
- 02Why does my gym use kg on the bar but lbs on the dumbbells?
- Plenty of gyms mix the two, usually because the barbell plates and the dumbbell rack were bought at different times or in different markets. An Olympic barbell is 20 kg, which is 44 lbs, not the 45 lbs people often assume. That four-pound gap matters once you are loading percentages off a one-rep max.
- 03How tall am I in centimeters?
- Multiply your total inches by 2.54. Convert feet to inches first, so 5 foot 10 is 70 inches, which is 177.8 cm. Height in centimeters is what most calorie and body composition formulas expect.
- 04Is 1 mile exactly 1.6 km?
- Close, but not exact. A mile is 1.6093 km. Over a 5 km run the rounding costs you about 15 meters, which does not matter. Over a marathon it is nearly half a kilometer, which does.