Temperature Converter

Enter a temperature, select its current scale, and choose the scale you want to convert to.

The main result shows the selected target scale, while the compact equivalents panel shows the same physical temperature on the other three scales.

Use Swap to reverse the selected scales. The unrounded converted value becomes the new source value.

The input supports negative values, grouped numbers, decimals, and scientific notation, provided the temperature is not below absolute zero.

Temperature scales cannot all be converted using one multiplication factor because Celsius and Fahrenheit have different zero points.

The calculator first converts the source value to kelvin and then converts that kelvin value to the selected target scale.

Using kelvin as the common reference keeps absolute-zero validation consistent across all four scales.

The kelvin, symbol K, is the SI base unit of thermodynamic temperature.

Its modern definition fixes the numerical value of the Boltzmann constant.

Kelvin begins at absolute zero and uses increments equal in size to Celsius degrees.

The symbol is K, not °K. Kelvin values are written without a degree sign.

Celsius temperature is related to thermodynamic temperature by an exact offset of 273.15.

Zero degrees Celsius equals exactly 273.15 K.

One Celsius degree and one kelvin represent the same temperature interval, although the scales have different zero points.

Celsius is widely used for weather, cooking, medicine, science, and everyday temperature reporting.

Fahrenheit uses a different zero point and smaller degree size than Celsius.

A temperature of 32 °F equals 0 °C, while 212 °F equals 100 °C.

One Celsius interval equals 1.8 Fahrenheit intervals.

The exact value conversion is °F = °C × 9/5 + 32.

Rankine is an absolute temperature scale that begins at absolute zero.

Its degree has the same size as a Fahrenheit degree.

One Rankine degree equals 5/9 kelvin, while one kelvin equals 1.8 Rankine degrees.

Rankine is encountered mainly in selected US engineering and thermodynamic work.

Celsius and Fahrenheit developed as practical thermometer scales with different reference points and degree sizes.

Kelvin and Rankine are absolute scales whose zero represents absolute zero.

Kelvin combines an absolute zero point with Celsius-sized increments, while Rankine combines an absolute zero point with Fahrenheit-sized increments.

Modern science and metrology use kelvin as the SI thermodynamic-temperature unit, while Celsius and Fahrenheit remain common in everyday applications.

Absolute zero is 0 K.

The equivalent values are exactly −273.15 °C, −459.67 °F, and 0 °R under the scale relationships used here.

The calculator allows the exact boundary and rejects lower values.

A small floating-point tolerance is normalized to zero so a valid absolute-zero conversion does not display a tiny negative Kelvin or Rankine value.

A temperature value identifies a point on a scale and may require both multiplication and an offset.

A temperature interval describes a difference between two temperatures and does not use the scale's zero-point offset.

For example, 20 °C converts to 68 °F as a temperature value, but an increase of 20 °C equals an increase of 36 °F.

One kelvin interval equals one Celsius-degree interval, while one Rankine-degree interval equals one Fahrenheit-degree interval.

The table uses the same formulas as the live converter.

Results that do not terminate are rounded to no more than four decimal places.

Reference temperatures can help make conversions easier to understand.

Water freezing and boiling points depend on pressure, water composition, and measurement conditions, so they are practical approximations rather than modern scale definitions.

Room and body temperatures are also approximate and vary with the environment, person, measurement site, and instrument.

Celsius and Fahrenheit have the same numerical value at −40.

Substituting −40 into °F = °C × 9/5 + 32 returns −40 °F.

This is the only point at which the two scale readings are numerically equal.

The scale relationships are retained without visible rounding during calculation.

Ordinary results display up to four decimal places, while very small or large values may use scientific notation.

Exact formulas do not make a measured temperature exact.

Thermometer calibration, sensor resolution, response time, location, pressure, and measurement method determine practical uncertainty.

Temperature and thermal energy are related but are not the same quantity.

Converting a temperature does not determine how much heat an object contains or how much energy is required to warm it.

Heat calculations require additional information such as mass, specific heat capacity, phase, and sometimes pressure.

Temperature conversion runs entirely in the browser.

Entered values and selected scales are not uploaded, added to a public URL, or permanently stored.

Clipboard access is requested only when the result copy control is used.