Celsius to Fahrenheit Converter

Celsius puts 0 at the freezing point of water and 100 at its boiling point at sea level. Fahrenheit uses 32 and 212 for the same two points, so the scales differ in both step size and starting point. That is why the conversion multiplies by 9/5 and then adds 32.

1. 1

   Enter a value

   Type a number into the From box. It starts at 1 so you can see the basic ratio straight away. Thousands separators such as 1,250.5 are accepted.

2. 2

   Choose your units

   This page opens with its own units selected. Use either dropdown to pick any other unit in the category, or tap a unit in the all-units list to make it the target.

3. 3

   Read the result

   The answer updates as you type and the matching formula is shown underneath. There is no Convert button to press.

4. 4

   Swap, copy or clear

   Swap reverses the direction, Copy Result copies a line such as 1 km = 0.621371 mi, and Clear empties the input so you can start again.

Input

• Supported
  Whole numbers25
• Supported
  Decimal numbers2.75

  Use a dot as the decimal separator.

• Supported
  Negative numbers-40

  Calculated for every unit. Quantities such as length or weight are normally positive, while temperatures can be negative.

• Supported
  Thousands separators1,250.5

  Commas must group digits in threes. 1,234 is read as one thousand two hundred thirty-four.

• Supported
  Scientific notation1.5e6

  Useful for very large or very small values (1.5e6 = 1,500,000).

• Not supported
  Comma as decimal mark2,5

  Type 2.5 instead.

• Not supported
  Fractions1/2

  Type 0.5 instead.

• Not supported
  Numbers with unit text5 km

  Enter only the number and choose the unit from the dropdown.

Output

Results use US English formatting (1,234.56) and show up to 2 decimal places with trailing zeros removed. Very small results appear in scientific notation, such as 9.0949e-13, instead of rounding to zero.

Units available in this converter

• Celsius (°C)
• Fahrenheit (°F)
• Kelvin (K)

Common values for the units currently selected above, in both directions.

Tips

• -40 is the one point where both scales show the same number.
• For a rough weather estimate, double the Celsius value and add 30. 20 °C gives about 70 °F, while the exact answer is 68 °F.

• Converts a temperature reading, not a temperature difference. A change of 10 °C is a change of 18 °F, using 9/5 without the +32 offset.
• Values below absolute zero (0 K, -273.15 °C, -459.67 °F) are physically impossible. The tool still calculates them but shows a warning.
• Rankine and Réaumur scales are not supported.
• Results show up to 2 decimal places. Values are not rounded during calculation, and a non-zero result that would display as 0 is shown in scientific notation.