Enter a temperature in Celsius (°C), Fahrenheit (°F), or Kelvin (K) and get instant conversions to all three scales. Type into any of the three input fields — Celsius, Fahrenheit, or Kelvin — and the Temperature Converter calculates the equivalent values using standard formulas like °F = (°C × 9/5) + 32.
Fahrenheit (°F)
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Celsius (°C)
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Kelvin (K)
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Rankine (°R)
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To convert Celsius to Fahrenheit, multiply the Celsius value by 9/5 (or 1.8) and then add 32. The formula is: °F = (°C × 9/5) + 32. For example, 100°C equals (100 × 1.8) + 32 = 212°F.
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit value and then multiply by 5/9. The formula is: °C = (°F − 32) × 5/9. For example, 32°F equals (32 − 32) × 5/9 = 0°C.
Absolute zero is the lowest possible temperature, equal to 0 Kelvin. This corresponds to −273.15°C and −459.67°F. At absolute zero, all molecular motion theoretically stops.
The only temperature where Celsius and Fahrenheit scales intersect is −40 degrees. That means −40°C equals exactly −40°F. You can verify this using the conversion formula: (−40 × 9/5) + 32 = −40.
Kelvin and Celsius use the same scale increment — a difference of 1°C equals a difference of 1 K. The only difference is the starting point: Kelvin starts at absolute zero, while Celsius sets 0 at the freezing point of water. To convert, simply add or subtract 273.15: K = °C + 273.15.
A few key reference temperatures: water freezes at 0°C / 32°F / 273.15 K, water boils at 100°C / 212°F / 373.15 K, normal human body temperature is about 37°C / 98.6°F / 310.15 K, and room temperature is typically around 20–22°C / 68–72°F.
The Fahrenheit scale was developed by Daniel Gabriel Fahrenheit in the early 18th century and adopted in the US and a few other countries. Most of the world transitioned to Celsius (part of the metric system) due to its simpler base-10 relationship and scientific utility. The US has retained Fahrenheit largely due to historical convention and cultural familiarity.
Rankine (°R) is an absolute temperature scale based on Fahrenheit, similar to how Kelvin is based on Celsius. The relationship is: °R = °F + 459.67. Like Kelvin, Rankine starts at absolute zero and is primarily used in certain engineering fields in the United States.