Temperature Converter

Enter a temperature and the scale it's in. The converter shows the equivalent in Celsius, Fahrenheit and Kelvin, plus Rankine as a bonus — all from the exact conversion formulas.

Temperature

From scale

Enter a temperature and press Convert temperature.

The conversion formulas

Every conversion goes through Celsius as the hub. First turn the input into Celsius, then turn Celsius into each target scale:

°F = °C × 9 ÷ 5 + 32 K = °C + 273.15 °C = (°F − 32) × 5 ÷ 9 °C = K − 273.15

Rankine is an absolute Fahrenheit scale: °R = °F + 459.67. Celsius and Kelvin share the same degree size; Fahrenheit and Rankine share theirs.

Worked example

Convert 100 °C (the boiling point of water at sea level) to the other scales:

To Fahrenheit: 100 × 9 ÷ 5 + 32 = 212 °F.

To Kelvin: 100 + 273.15 = 373.15 K.

To Rankine: 212 + 459.67 = 671.67 °R.

Reference points

Point	°C	°F	K
Absolute zero	−273.15	−459.67	0
Water freezes	0	32	273.15
Body temperature	37	98.6	310.15
Water boils	100	212	373.15

Note: −40° is the one temperature where Celsius and Fahrenheit are equal (−40 °C = −40 °F). It's a handy sanity check for any conversion tool.

Frequently asked questions

How do I convert Celsius to Fahrenheit?

Multiply the Celsius value by 9/5 (or 1.8) and add 32. For example, 100 °C × 1.8 + 32 = 212 °F, the boiling point of water at sea level.

How do I convert Celsius to Kelvin?

Add 273.15 to the Celsius value. The Kelvin scale uses the same degree size as Celsius but starts at absolute zero, so 0 °C is 273.15 K and 100 °C is 373.15 K.

What is absolute zero in each scale?

Absolute zero, the point where molecular motion stops, is 0 K, which equals −273.15 °C and −459.67 °F. It is also 0 on the Rankine scale.

What is the Rankine scale?

Rankine is an absolute scale that uses Fahrenheit-sized degrees, mainly in some US engineering work. Convert from Fahrenheit by adding 459.67, so 32 °F (freezing) is 491.67 °R.

Mustafa Bilgic · Editor, Calcool
Conversions use the exact internationally defined relationships between the Celsius, Fahrenheit, Kelvin and Rankine scales (0 °C = 273.15 K). For the SI definition of the kelvin, see the BIPM SI Brochure. Last updated 20 June 2026.

Temperature Converter

The conversion formulas

Worked example

Reference points

Frequently asked questions

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