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Why Unit Conversion Matters
Whether you’re cooking with a recipe from another country, traveling abroad, or working on an engineering project, converting between measurement units is something most of us need to do regularly.
Common Length Conversions
The most frequently needed length conversions:
| From | To | Formula |
|---|---|---|
| Inches | Centimeters | × 2.54 |
| Feet | Meters | × 0.3048 |
| Miles | Kilometers | × 1.609 |
| Centimeters | Inches | × 0.3937 |
| Meters | Feet | × 3.281 |
| Kilometers | Miles | × 0.6214 |
Example: Convert 5’10” to centimeters
5 feet = 5 × 30.48 = 152.4 cm
10 inches = 10 × 2.54 = 25.4 cm
Total = 152.4 + 25.4 = 177.8 cm
Common Weight Conversions
| From | To | Formula |
|---|---|---|
| Pounds | Kilograms | × 0.4536 |
| Kilograms | Pounds | × 2.205 |
| Ounces | Grams | × 28.35 |
| Stones | Kilograms | × 6.35 |
Example: Convert 150 lbs to kg
150 × 0.4536 = 68.04 kg
Temperature Conversions
Temperature conversions use different formulas than simple multiplication:
- Celsius to Fahrenheit:
°F = (°C × 9/5) + 32 - Fahrenheit to Celsius:
°C = (°F - 32) × 5/9 - Celsius to Kelvin:
K = °C + 273.15
Example: Convert 72°F to Celsius
°C = (72 - 32) × 5/9
°C = 40 × 5/9
°C ≈ 22.2°C
Volume Conversions
| From | To | Formula |
|---|---|---|
| Gallons | Liters | × 3.785 |
| Liters | Gallons | × 0.2642 |
| Cups | Milliliters | × 236.6 |
| Fluid ounces | Milliliters | × 29.57 |
Free Unit Converter
Convert between length, weight, temperature, and volume units instantly.
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Frequently Asked Questions
How do you convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (or 1.8), then add 32. The formula is: F = (C x 9/5) + 32. For example, 25 degrees Celsius = (25 x 1.8) + 32 = 77 degrees Fahrenheit.
How many centimeters are in an inch?
One inch equals exactly 2.54 centimeters. To convert inches to centimeters, multiply by 2.54. To convert centimeters to inches, divide by 2.54 (or multiply by 0.3937).
How do you convert pounds to kilograms?
Multiply the weight in pounds by 0.4536 to get kilograms. For example, 150 pounds = 150 x 0.4536 = 68.04 kilograms. To convert back, multiply kilograms by 2.205.
Unit conversions come up frequently in health and fitness calculations like BMI, and in engineering work. For Mac users, see our guide on the best calculator apps for Mac that include built-in unit conversion.
Convert Units in Notes Calculator
Notes Calculator has built-in conversion for 40+ unit types. Just use to, in, or as between units:
# Length
5 feet 10 inches in cm
marathon = 26.2 miles in km
# Weight
150 lbs to kg
250 grams in ounces
# Temperature
72 fahrenheit to celsius
-40 celsius in fahrenheit
# Volume
2 gallons in liters
500 ml to cups
The app supports lengths, weights, temperatures, volumes, speeds, pressures, digital data (bytes, megabytes), areas, and even shoe sizes. You can also mix units in arithmetic — 5 km + 300 m automatically converts to a common unit. For currencies, type 100 USD in EUR to convert between 100+ currencies with live exchange rates.