Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin and Rankine. Instant temperature conversion with formula.
Common conversions
100 °C =
212
°F (Fahrenheit)
100 °C in all units
How to Use
- 1
Enter a temperature
Type the temperature value to convert.
- 2
Select input scale
Choose Celsius, Fahrenheit, or Kelvin as your input.
- 3
See all results
Equivalent temperatures in all three scales appear instantly.
How It Works
This tool converts between Celsius, Fahrenheit, Kelvin, and Rankine — the four temperature scales you're likely to encounter in weather, cooking, science, and engineering contexts.
The conversion formulas
°F = (°C × 9/5) + 32, and the reverse: °C = (°F − 32) × 5/9. Kelvin (used in science) has the same size degree as Celsius but starts at absolute zero: K = °C + 273.15. Rankine does the same for Fahrenheit: °R = °F + 459.67.
Why Kelvin and Rankine have no negative values in practice
Both scales start at absolute zero — the theoretical point where molecular motion stops (−273.15°C / −459.67°F) — so temperatures in Kelvin or Rankine are essentially never negative in any real physical context, unlike Celsius and Fahrenheit.
Examples
Boiling and body temperature
Water boils at 100°C = 212°F = 373.15K. Normal human body temperature, 37°C, converts to 98.6°F — the commonly quoted "normal" reading.
A cold day
−10°C converts to (−10 × 9/5) + 32 = 14°F, and to 263.15K.
Common Use Cases
- Converting oven temperatures between recipes written in °F and °C
- Understanding weather forecasts when traveling between countries using different scales
- Science and engineering calculations that require Kelvin
- Checking fever thresholds when a thermometer or medical device reports in the other scale
Tips
- US recipes and oven dials use Fahrenheit almost universally, while most of the rest of the world uses Celsius — double check which scale a recipe assumes before converting, since a 350 reading means very different oven temperatures in each.
- For quick mental Celsius-to-Fahrenheit estimates, doubling the Celsius figure and adding 30 gets you close (exact for the formula would be ×1.8 +32) — good enough for weather, not for scientific work.
Frequently Asked Questions
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