Temperature Converter

Enter a temperature and choose the scale you are converting from. The equivalent temperatures update immediately in Celsius, Fahrenheit, Kelvin, and Rankine.

Use temperature-value conversion for readings such as 20 °C or 68 °F. Use temperature-difference conversion when the number describes a rise, fall, or interval rather than a point on a temperature scale.

To convert Celsius to Fahrenheit, multiply the Celsius temperature by 9/5 and then add 32.

For example, 20 °C equals 68 °F, 0 °C equals 32 °F, and 100 °C equals 212 °F.

To convert Fahrenheit to Celsius, subtract 32 and then multiply by 5/9.

For example, 68 °F equals 20 °C and 32 °F equals 0 °C. Celsius and Fahrenheit have the same numerical value at −40, so −40 °C equals −40 °F.

Fahrenheit can be converted directly to kelvin with K = (°F + 459.67) × 5/9.

For example, 0 °F is approximately 255.3722 K, 5 °F equals 258.15 K, and 100 °F is approximately 310.9278 K.

Celsius and kelvin use intervals of the same size, but their zero points are different. Kelvin equals Celsius plus exactly 273.15.

This means 0 °C equals exactly 273.15 K, 20 °C equals 293.15 K, and 310.15 K equals 37 °C.

A temperature value identifies a position on a scale. A temperature difference describes the size of a change between two temperatures.

The distinction matters because scale offsets apply to values but not to differences. A temperature of 20 °C equals 68 °F, but a temperature increase of 20 °C equals an increase of 36 °F rather than 68 °F.

Absolute zero is 0 K. The corresponding scale values are exactly −273.15 °C, −459.67 °F, and 0 °R.

Absolute temperature values below these limits are physically outside the supported temperature scales, so the converter rejects them rather than returning a misleading result.

The SI unit name is kelvin and its symbol is K. A temperature is written as 300 K, not 300 °K.

A change of one kelvin has the same magnitude as a change of one Celsius degree, although the Celsius and Kelvin scales have different zero points.

Rankine is an absolute temperature scale beginning at absolute zero, like Kelvin, but it uses Fahrenheit-sized intervals.

One kelvin equals 1.8 Rankine degrees. Rankine appears mainly in some engineering and thermodynamic applications rather than everyday weather reporting.

The four scales differ in their zero points, interval sizes, and typical uses.

Celsius and Kelvin share the same interval size. Fahrenheit and Rankine share the same interval size. Kelvin and Rankine are absolute scales.

These examples cover common Celsius, Fahrenheit, and Kelvin conversions along with absolute zero and the −40 point where Celsius and Fahrenheit readings match.

The converter keeps the underlying converted value before formatting the number for display.

Reference values can make an unfamiliar temperature scale easier to understand.

Freezing and boiling temperatures of water are practical reference points rather than universal physical constants: actual phase-change temperatures depend on pressure and other conditions. Room and body temperatures are also approximate.

Temperature describes thermal state, while heat refers to energy transferred because of a temperature difference.

Converting °C to °F or K does not determine how much thermal energy an object contains or how much energy is required to heat it. Those calculations need additional information such as mass and specific heat capacity.

The conversion formulas are applied before the result is formatted for display, so intermediate values are not intentionally shortened.

A mathematically exact conversion does not make a measured temperature exact. Thermometer calibration, sensor resolution, placement, response time, and measurement conditions can affect the original reading.