Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin and Rankine instantly.
Convert Celsius, Fahrenheit, Kelvin and Rankine
Temperature scales differ in two ways: where zero sits, and how big a degree is. Celsius puts zero at water’s freezing point, Fahrenheit at a colder reference and uses smaller degrees, while Kelvin starts at absolute zero — the point where molecular motion stops — and uses Celsius-sized degrees.
Because the zero points differ, you cannot simply multiply between them; there is always an offset. This converter shows all four scales at once so the relationship is visible rather than something you have to trust.
Key features
- All four scales simultaneously — change one and the other three update instantly.
- Common reference points — one tap for freezing, room temperature, body heat, boiling and oven settings.
- Absolute zero check — a physically impossible temperature is flagged rather than silently converted.
- Two-decimal precision — enough for cooking, weather and laboratory work alike.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: Temperature Converter
- Enter a temperature
Type the number into the value field. - Select the scale it is in
Celsius, Fahrenheit, Kelvin or Rankine. - Read all four results
Every scale updates at once, so no second conversion is needed. - Use a preset for a quick check
The reference buttons jump straight to well-known points like body temperature or a 180 °C oven.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Converters |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. So 20 °C × 1.8 = 36, plus 32 = 68 °F. To reverse it, subtract 32 first and then multiply by 5/9 — the order matters.
At what temperature are Celsius and Fahrenheit equal?
At −40. That is the single crossing point of the two scales, which is why −40 °C and −40 °F are the same temperature and why the figure appears so often in cold-weather specifications.
What is absolute zero?
0 kelvin, equal to −273.15 °C or −459.67 °F. It is the theoretical point at which particles have minimum energy. Nothing can be colder, so any input implying a negative kelvin value is flagged as impossible.
What is Rankine used for?
Rankine is an absolute scale using Fahrenheit-sized degrees, still used in some US engineering and thermodynamics work — particularly aerospace and HVAC — where an absolute scale is needed but imperial units are the convention.