Free Temperature Converter
Whether you are following an American recipe in Fahrenheit, checking a weather forecast in Celsius, or working through a physics problem in Kelvin, this free temperature converter gives you the answer instantly. Type any value, pick your scales, and see precise conversions using the exact scientific formulas — plus the temperature on all three scales at a glance.
Value in all temperature scales
| Unit | Value |
|---|
How to Use the Temperature Converter
- Enter a temperature in the input box.
- Choose the scales to convert from and to — use the ⇄ button to swap them.
- See the result instantly, plus the temperature on every scale in the table below.
- Conversions use the exact formulas, and values below absolute zero (−273.15 °C) are rejected.
Features
Convert between Celsius, Fahrenheit and Kelvin in any direction with live results as you type. A one-click swap button flips the conversion, and the full table shows your value on every scale simultaneously. Inputs below absolute zero (−273.15 °C) are flagged, since they are not physically possible.
Benefits & Use Cases
Cooks converting oven temperatures, travelers reading foreign weather reports, students checking homework, and engineers sanity-checking specs all get answers in a fraction of a second. Because every conversion happens in your browser, results appear the moment you type — with zero waiting and zero tracking.
Tips
Remember that a change of 1 °C equals 1.8 °F, but the scales start at different zeros — that is why the +32 offset matters. For weather, −40 is the point where both scales meet. When precision matters in science, Kelvin removes negative numbers entirely.
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (1.8) and add 32. For example, 25 °C × 1.8 + 32 = 77 °F. The tool above applies this exact formula instantly.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit temperature, then multiply by 5/9. For example, (77 − 32) × 5/9 = 25 °C.
What is the formula for Celsius to Kelvin?
Add 273.15 to the Celsius value. So 25 °C = 298.15 K. Kelvin never goes below zero, which is why scientists prefer it.
Why does the converter reject some temperatures?
Any value below absolute zero (−273.15 °C, −459.67 °F, 0 K) is physically impossible, so the tool flags it instead of converting.
Is this temperature converter free?
Yes — every NToolHub converter is completely free, requires no sign-up, and runs entirely in your browser.
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