Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin instantly in your browser.
About the Temperature Converter
The Temperature Converter turns any temperature into another scale instantly — Celsius (°C), Fahrenheit (°F), and Kelvin (K). Type a number, pick the scale you have and the scale you want, and the answer appears immediately. All the math runs in your browser, so it's instant and keeps working offline once the page has loaded.
Temperature conversions come up more often than you might expect: following a recipe written for another country's oven, reading a weather forecast while travelling, checking a fever against a chart from a different region, or doing science and engineering homework in Kelvin. Instead of hunting for the right formula or reaching for a calculator, you get a clean, live result the moment you type. The tool always converts through Celsius as its base, so every pairing — Fahrenheit to Kelvin, Kelvin to Fahrenheit, and everything in between — stays consistent and accurate.
How to use
- Enter a value in the "From" box — it can be positive, negative, or a decimal.
- Choose the scale you're converting from in the first dropdown.
- Choose the scale you want in the second dropdown — the result updates as you type.
- Use the ⇄ swap button to reverse the direction (for example, switch from "Celsius → Fahrenheit" to "Fahrenheit → Celsius") without re-entering anything.
The converter uses the standard, internationally recognized formulas. Celsius and Fahrenheit meet at exactly -40 degrees, and Kelvin is simply Celsius shifted by 273.15 so that 0 K sits at absolute zero. Results are shown rounded to a sensible couple of decimal places, with trailing zeros trimmed so the display stays tidy — a whole-number answer looks like a whole number, not "20.00".
Common conversions
- 0 °C = 32 °F (water freezes)
- 100 °C = 212 °F (water boils at sea level)
- 37 °C = 98.6 °F (normal body temperature)
- -40 °C = -40 °F (the point where both scales meet)
- 0 °C = 273.15 K
- 20 °C = 68 °F (comfortable room temperature)
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 (that is, 1.8) and add 32. For example, 25 °C × 1.8 = 45, plus 32 = 77 °F. This converter does that automatically the moment you type, so you never have to remember the formula — but it's handy to know for a quick mental estimate.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit value, then multiply by 5/9. For example, (98.6 − 32) × 5/9 = 37 °C. Selecting "Fahrenheit" as the "from" scale and "Celsius" as the "to" scale gives you this instantly, and the swap button lets you flip the direction with one click.
What is Kelvin and when would I use it?
Kelvin is the base unit of temperature in science and engineering. It uses the same size of degree as Celsius but starts at absolute zero — the coldest possible temperature — so there are no negative values. Zero Kelvin equals -273.15 °C. To convert, just add 273.15 to a Celsius value, or subtract it to go the other way. Physics, chemistry, and astronomy work almost always use Kelvin.
Can I convert negative temperatures?
Yes. Celsius and Fahrenheit both go well below zero, and the converter handles negatives without any trouble. Kelvin, however, cannot be negative because it starts at absolute zero — if you enter a Celsius value below -273.15, the equivalent Kelvin figure would fall below zero, which is not physically meaningful even though the arithmetic still produces a number.
Does this work without an internet connection?
Once the page has loaded, yes. Every calculation happens locally in your browser with no server involved, so conversions keep working even if you go offline. Nothing you type is sent anywhere or stored.
Why does the result sometimes look rounded?
To keep the display clean, results are rounded to two decimal places and trailing zeros are trimmed. For everyday cooking, weather, and health use this is more than precise enough. If you need extra decimal places for a lab measurement, you can apply the formula above to your exact value.
All conversions run entirely client-side in your browser — nothing you enter leaves your device.