Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin and more — step-by-step working shown.
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Common conversions from Celsius
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Temperature Converter
A temperature converter helps you switch between different ways of measuring how hot or cold something is. This is really useful when you're travelling to countries that use a different system, following a recipe from another part of the world, or studying science where specific scales are needed.
The main challenge with temperature conversion is that the scales (Celsius, Fahrenheit, and Kelvin) don't just start at different points; they also increase at different rates. This means you can't just add or subtract a fixed number; you often need to multiply or divide as well.
How to Convert Celsius to Fahrenheit Manually
Multiply by 9
Take your temperature in Celsius and multiply it by 9. For example, if you have 20°C, you'd calculate 20 × 9 = 180.
Divide by 5
Next, take the result from Step 1 and divide it by 5. Using our example, 180 ÷ 5 = 36.
Add 32
Finally, add 32 to the number you got in Step 2. So, 36 + 32 = 68. Therefore, 20°C is equal to 68°F. The full formula is: F = (C × 9 / 5) + 32.
Conversions in context
Travel: UK summer day to US forecast
25 Celsius → 77 Fahrenheit
Cooking: US recipe oven temperature
375 Fahrenheit → 191 Celsius
Science: Room temperature in a lab
20 Celsius → 293.15 Kelvin
Everyday Life: Old thermometer reading
68 Fahrenheit → 20 Celsius
Weather: Freezing point of water
0 Celsius → 32 Fahrenheit
School: Absolute zero temperature
0 Kelvin → -273.15 Celsius
Common mistakes to avoid
- To convert 20°C to Fahrenheit, I'll do 20 + 32 = 52, then 52 * 9 / 5 = 93.6°F:The order of operations is incorrect. You must multiply and divide first, then add 32. Adding 32 too early gives a much higher result. The correct calculation is (20 * 9 / 5) + 32 = (180 / 5) + 32 = 36 + 32 = 68°F.
- To convert 70°F to Celsius, I'll multiply by 9/5 and then add 32:This is the formula for Celsius to Fahrenheit. For Fahrenheit to Celsius, you need to subtract 32 first, then multiply by 5/9. The correct calculation is (70 - 32) 5 / 9 = 38 5 / 9 = 190 / 9 ≈ 21.1°C.
- To convert 25°C to Kelvin, I'll multiply 25 by 273.15:Kelvin is an absolute scale that starts at absolute zero. You simply add 273.15 to the Celsius temperature, not multiply. The correct calculation is 25 + 273.15 = 298.15 K.
Questions people ask
How do I convert Celsius to Fahrenheit without a calculator?
A quick approximation is to double the Celsius temperature, then subtract 10% of that result, and finally add 32. For example, 20°C doubled is 40. 10% of 40 is 4. 40 - 4 = 36. Add 32 gives 68°F, which is the exact answer for 20°C. This method works well for many common temperatures.
What temperature is the same in both Celsius and Fahrenheit?
The temperature at which both Celsius and Fahrenheit scales read the same value is -40 degrees. So, -40°C is exactly equal to -40°F. This is a unique point where the two scales converge.
What is Kelvin and why is it used in science?
Kelvin is an absolute temperature scale where 0 Kelvin (0 K) represents absolute zero, the lowest possible temperature where all molecular motion stops. It's used in science because it avoids negative numbers and simplifies many physical laws and calculations, especially in thermodynamics and cryogenics. Unlike Celsius and Fahrenheit, Kelvin does not use a degree symbol.
Why does the USA still use Fahrenheit?
The USA continues to use Fahrenheit primarily due to historical reasons and cultural inertia. When most of the world adopted the metric system and Celsius in the 20th century, the cost and effort of converting all weather stations, industrial equipment, and public education to Celsius were deemed too high. Liberia and Myanmar are the only other countries that still officially use Fahrenheit.
What is normal body temperature in both scales?
Normal human body temperature is generally considered to be 37°C (Celsius). In Fahrenheit, this is equivalent to 98.6°F. Slight variations around these values are common and still considered healthy.