Temperature Converter
A temperature converter changes a reading between scales such as Celsius, Fahrenheit and Kelvin. The formulas are °F = °C × 9/5 + 32 and K = °C + 273.15. This tool converts as you type, shows the formula for the pair you choose, supports Rankine, and warns when a value is below absolute zero.
Free, no signup. Runs entirely in your browser; files and text are not uploaded.
How to use the Temperature Converter
- Enter the temperature in the Value box. Negative numbers are allowed.
- Choose the scale you have in From, such as Celsius.
- Choose the scale you want in To, such as Fahrenheit.
- Read the result and the formula used, or copy the result.
Features
- Celsius, Fahrenheit, Kelvin and Rankine
- Shows the exact formula for each pair of scales
- Absolute-zero check (0 K = −273.15 °C = −459.67 °F)
- Reference table: freezing, room, body and boiling temperatures
- All-scales table, presets and copy buttons
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 (1.8) and add 32. For example, 25 °C × 1.8 + 32 = 77 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32 and multiply by 5/9. For example, (98.6 °F − 32) × 5/9 = 37 °C.
At what temperature are Celsius and Fahrenheit equal?
At −40. −40 °C is exactly −40 °F.
Why is there no degree sign on Kelvin?
Kelvin is an absolute SI unit, so it is written as K without a degree sign. 0 K is absolute zero, the lowest possible temperature.
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Built and reviewed by Naqash Thaheem, Technical Project Manager. Last reviewed 2026-09-24.