Temperature Converter
Free online Temperature Converter to convert between Celsius, Fahrenheit, and Kelvin instantly.
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The Temperature Converter instantly converts between Celsius, Fahrenheit, and Kelvin. Whether you're reading a foreign weather forecast, following an overseas recipe, or working through a science problem, you get an exact temperature in one click.
Three Scales, One Tool
The world uses three temperature scales for three different reasons. Celsius is the everyday standard almost everywhere, Fahrenheit rules US weather and cooking, and Kelvin is the language of science. Converting between them by hand means remembering three formulas; this tool does it for you, exactly.
How to Convert
- Enter the temperature.
- Choose the from and to scales.
- Read the converted result instantly.
The Conversion Formulas
| Conversion | Formula | Example |
|---|---|---|
| °C → °F | (°C × 9/5) + 32 | 20°C = 68°F |
| °F → °C | (°F − 32) × 5/9 | 98.6°F = 37°C |
| °C → K | °C + 273.15 | 0°C = 273.15 K |
Two Reference Points Worth Memorizing
Two checkpoints make conversions sanity-check themselves. First, −40° is the same in Celsius and Fahrenheit — the one temperature where the scales meet. Second, 37°C equals 98.6°F, normal body temperature. If a conversion lands near these known pairs, you can trust the math at a glance.
Kelvin and Absolute Zero
Kelvin starts at absolute zero — 0 K, equal to −273.15°C — the theoretical point where molecular motion halts and nothing can be colder. Because it has no negative numbers, scientists prefer it for physics and chemistry. Converting Celsius to Kelvin is the simplest of all: just add 273.15.
Everyday Reasons to Convert
- Weather — read forecasts in an unfamiliar scale.
- Cooking — set the oven correctly for foreign recipes.
- Science — work in Kelvin for calculations.
- Travel — make sense of local temperature readings.
Accurate and Free
The converter applies exact formulas at full precision, all in your browser. Convert as often as you need, free.
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 and add 32. For example, 20°C becomes (20 × 9/5) + 32 = 68°F. The converter does this instantly, but the formula is worth knowing for quick mental estimates.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit value, then multiply by 5/9. For example, 98.6°F becomes (98.6 − 32) × 5/9 = 37°C, the normal human body temperature.
What is Kelvin used for?
Kelvin is the scientific temperature scale that starts at absolute zero, the coldest possible temperature. It's used in physics and chemistry because it has no negative values. To convert Celsius to Kelvin, simply add 273.15.
What is absolute zero?
Absolute zero is 0 Kelvin, equal to −273.15°C or −459.67°F — the theoretical point where molecular motion stops. Nothing can be colder, which is why Kelvin starts there.
At what temperature do Celsius and Fahrenheit meet?
They read the same at −40 degrees: −40°C equals −40°F. It's the single point where the two scales coincide, a useful checkpoint for verifying a conversion.
Why do recipes use different temperature scales?
Recipes follow their country's convention — Celsius in most of the world, Fahrenheit in the US. Converting oven temperatures accurately prevents under- or over-cooking when following a recipe from abroad.
Is the conversion accurate?
Yes. It applies the exact formulas at full precision, so results are reliable for science, cooking, and weather alike.
Is this tool free?
Yes — free, instant, and unlimited, with no signup.