Student resources
Grades 5-12
Common Unit Conversion Formulas for Students
A conversion formula changes a value from one unit to another. The most reliable method is to multiply by a conversion factor or use a known formula.
Key ideas
- Write the starting value with its unit before converting.
- Choose the conversion factor that cancels the old unit.
- Multiply or divide carefully, then label the final answer.
- Check whether the answer is reasonable.
Useful Formulas
| Convert | Formula | Example |
|---|---|---|
| Kilograms to pounds | lb = kg x 2.20462 | 10 kg = 22.0462 lb |
| Pounds to kilograms | kg = lb x 0.453592 | 10 lb = 4.5359 kg |
| Centimeters to inches | in = cm x 0.393701 | 10 cm = 3.937 in |
| Kilometers to miles | mi = km x 0.621371 | 5 km = 3.1069 mi |
| Celsius to Fahrenheit | F = C x 9 / 5 + 32 | 20°C = 68°F |
| Minutes to hours | hr = min / 60 | 90 min = 1.5 hr |
Practice questions
Convert 6 kilometers to miles.
Answer: About 3.728 miles
Convert 30°C to Fahrenheit.
Answer: 86°F
Convert 120 minutes to hours.
Answer: 2 hours