Temperature Conversion Formulas
All conversions are performed via Celsius as the base unit. Below are the standard formulas used by this tool.
Boiling point in numbers: 100°C to °F
Plug water's boiling point into the Celsius-to-Fahrenheit formula °F = (°C × 9/5) + 32. Start with 100°C. Multiply by 9/5: 100 × 1.8 = 180. Then add 32: 180 + 32 = 212°F. That is why a kettle hits 212°F at sea level. Run the same value the other way with °C = (°F − 32) × 5/9: (212 − 32) × 5/9 = 180 × 0.5556 = 100°C — back where you started.
How do I convert Celsius to Fahrenheit?
Multiply by 9/5, then add 32: °F = (°C × 9/5) + 32. Example: 100°C → 212°F (water's boiling point at sea level).
How do I convert Celsius to Kelvin?
Add 273.15 to the Celsius value: K = °C + 273.15. Kelvin is the SI unit for thermodynamic temperature and starts at absolute zero — there are no negative Kelvin values.
What temperature is the same in Celsius and Fahrenheit?
At −40°, both scales read the same value. This is because the two formulas intersect at that exact point — a useful sanity-check when doing manual conversions.
What is absolute zero in Celsius and Fahrenheit?
Absolute zero is 0 K = −273.15°C = −459.67°F. The Rankine scale also starts at absolute zero but uses Fahrenheit-sized degrees, so 0°R = 0 K.
Precision notes and when to double-check
The formulas above are exact, but the displayed results are rounded for readability, so a value such as 37°C → 98.6°F may hide further decimal places. That rounding is fine for cooking, weather, thermostats, and everyday conversions, but it is not intended for scientific-grade or laboratory work where you need full floating-point precision or a specific number of significant figures — carry the raw formula through your own calculation in those cases. This tool also assumes you are entering a temperature, not a temperature difference: a 10-degree change in Celsius is an 18-degree change in Fahrenheit, but the 32-degree offset only applies to absolute readings, not deltas. And while Kelvin and Rankine have no values below zero, the tool will still convert a physically impossible sub-absolute-zero input arithmetically — interpret such results with care.