Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin with real-time calculation.

  • Conversion
  • Runs in your browser
  • Free, no signup

How to use

How to Use Temperature Converter

  1. 1

    Enter a temperature

    Type the temperature value you want to convert.

  2. 2

    Select the unit

    Choose Celsius, Fahrenheit, or Kelvin as the source unit.

  3. 3

    View conversions

    See the temperature converted to all other units instantly.

The guide

Tested tool guide Math and conversion tools Checked July 30, 2026

What Temperature Converter does, with a checked example

This converter keeps Celsius, Fahrenheit, and kelvin values synchronized. Editing any one scale recalculates the other two and shows the formulas used. Reference points such as absolute zero, water freezing, room temperature, and water boiling provide quick reasonableness checks.

Worked example

A concrete input and expected output from the current implementation.

Input

20 degrees Celsius

Expected output

68 degrees Fahrenheit; 293.15 kelvin

Fahrenheit is 20 x 9/5 + 32, which equals 68. Kelvin is Celsius plus 273.15.

How the result is produced

1

Celsius and kelvin have equal-sized increments

Their numerical difference is an offset of 273.15. Kelvin is an absolute thermodynamic scale and its unit name is written without a degree symbol.

2

Fahrenheit changes scale and offset

Celsius-to-Fahrenheit conversion multiplies by 9/5 before adding 32. The inverse subtracts 32 and multiplies by 5/9.

Good uses

  • Translate a weather or cooking temperature.
  • Check a laboratory value across common scales.
  • Compare a conversion with known freezing and boiling points.

Limits and checks

  • Water boiling temperature depends on pressure.
  • Displayed values are rounded to four decimal places.
  • Kelvin values below zero are not physically meaningful in ordinary thermodynamics.

Common questions

At what value are Celsius and Fahrenheit equal?

They are both -40. Substituting -40 into either conversion formula produces -40 on the other scale.

Why is kelvin not written with a degree symbol?

The SI unit is the kelvin, symbol K. It is an absolute temperature unit rather than a degree scale label.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.