Unit converter for length, weight, temperature and more
Type in either box and the other converts live. US customary units on one side, metric on the other, across six categories.
The short answer
One inch is exactly 2.54 cm, one foot is 30.48 cm, and one pound is exactly 0.45359237 kg. So 5 ft 9 in is 175.26 cm, 150 lb is 68.0389 kg, and 350°F is 176.67°C. A US gallon is exactly 3.785411784 liters.
How it is calculated
cm = inches × 2.54; inches = feet × 12
kg = lb × 0.45359237
°C = (°F − 32) × 5 ÷ 9; °F = °C × 9 ÷ 5 + 32
liters = US gallons × 3.785411784
1 acre = 43,560 ft²; 1 mile = 5,280 ft
Worked example
A European recipe and a doctor's form both want metric. You are 5′9″ and 150 lb, the oven dial says 350°F, and you need 5 gallons of water.
- Height: (5 × 12 + 9) × 2.54 = 175.26 cm
- Weight: 150 × 0.45359237 = 68.0389 kg
- Oven: (350 − 32) × 5 ÷ 9 = 176.67°C
- Water: 5 × 3.785411784 = 18.9271 L
175.26 cm, 68.0389 kg, 176.67°C and 18.9271 liters
Quick reference table
| Height | Centimeters | Meters |
|---|---|---|
| 5′0″ | 152.4 cm | 1.524 m |
| 5′3″ | 160.02 cm | 1.6002 m |
| 5′6″ | 167.64 cm | 1.6764 m |
| 5′9″ | 175.26 cm | 1.7526 m |
| 6′0″ | 182.88 cm | 1.8288 m |
| 6′3″ | 190.5 cm | 1.905 m |
Special cases and common mistakes
- US and imperial gallons differ. A US gallon is 3.7854 L; the British imperial gallon is about 4.546 L, so a fuel-economy figure quoted in UK miles per gallon is not comparable to a US one.
- Oven temperatures are not exact conversions. 350°F works out to 176.67°C, and a metric recipe that says 180°C means 356°F, so the two are within a few degrees.
- Square feet do not scale like feet. 1 ft is 0.3048 m, but 1 ft² is 0.0929 m². A 1,500 ft² home is 139.35 m², and an acre is 4,046.86 m².
- Road speeds. 65 mph is 104.61 km/h, and a 100 km/h highway sign in Canada is 62.1371 mph.
Frequently asked questions
How do I convert feet and inches to cm?
Multiply feet by 12, add the inches, then multiply by 2.54. 5′9″ is (60 + 9) × 2.54 = 175.26 cm.
How many pounds are in a kilogram?
1 kg is 2.2046 lb, because a pound is defined as exactly 0.45359237 kg. 70 kg is 154.32 lb.
How do I convert Fahrenheit to Celsius?
Subtract 32, multiply by 5 and divide by 9. 98.6°F is 37°C and 32°F is 0°C.
How many liters are in a gallon?
A US gallon is exactly 3.785411784 liters, or 128 US fluid ounces. Four quarts make a gallon.
How many square feet are in a square meter?
1 m² is 10.7639 ft², and 1 ft² is 0.0929 m².
How fast is 100 km/h in mph?
62.1371 mph. To go the other way, 60 mph is 96.5606 km/h.
Sources
- NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement (Last reviewed: October 9, 2026)