Temperature Converter

Convert between Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Réaumur and Rømer. This tool is useful for weather, cooking, science, engineering checks, health context and international temperature comparisons. Enter a value in any temperature scale and every other scale updates in real time, with reference points, formulas and examples to help you check the result.

Convert temperature

Choose any input box and enter a temperature. The converter uses Celsius as the internal reference scale, then applies the correct offset formula for each target scale. This is important because temperature conversion is not always a simple multiplication.

Quick references

Full conversion table

Enter a temperature above to see all conversions.

Temperature reference guide

Common temperatures you might encounter in everyday life, science, and cooking.

Oven temperature guide

Common oven settings in °C, °F, and gas mark.

Description	°C	°F	Gas mark

Conversion formulas

How it works

Temperature conversions are different from most unit conversions because many temperature scales have different zero points. For example, 0°C and 0°F do not mean the same physical temperature. This means Celsius to Fahrenheit needs both multiplication and addition, while Celsius to Kelvin needs addition only.

This converter stores the entered value internally as Celsius. If you enter Fahrenheit, Kelvin, Rankine or another scale, the value is first converted into Celsius. The calculator then converts that Celsius value into every other temperature unit using the correct formula for each scale.

Formula used

The most common temperature conversion formulas are:

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

Other scales such as Rankine, Réaumur, Delisle, Newton and Rømer are less common, but they are included for science, history, study and specialist reference. The calculator applies each scale’s correct offset and ratio formula.

Worked example

Example: convert 20°C to Fahrenheit

Use the Celsius to Fahrenheit formula.

°F = (°C × 9/5) + 32
°F = (20 × 9/5) + 32
°F = 36 + 32 = 68°F

So, 20°C is 68°F.

Example: convert 300 K to Celsius

Kelvin converts to Celsius by subtracting 273.15.

°C = K − 273.15
°C = 300 − 273.15
°C = 26.85°C

So, 300 K is 26.85°C.

Common mistakes

Using multiplication only

Celsius and Fahrenheit need an offset. For example, 20°C is not 36°F; the correct answer is 68°F because you must add 32 after multiplying by 9/5.

Forgetting absolute zero

Kelvin starts at absolute zero. Temperatures below 0 K are not physically meaningful in normal thermodynamic use.

Confusing Rankine and Rømer

Both can use an R-style symbol, but they are different temperature scales with different formulas.

Rounding too early

For science, engineering or lab work, keep more decimal places during the calculation and only round the final answer.

Common questions

Why is temperature conversion not a simple multiplication? ⌄

Temperature scales often have different zero points. Celsius and Fahrenheit are offset from each other, so converting between them needs both multiplication and addition or subtraction.

At what temperature are Celsius and Fahrenheit the same? ⌄

Celsius and Fahrenheit are the same at −40 degrees. That means −40°C = −40°F.

Can Kelvin be negative? ⌄

In standard thermodynamic use, Kelvin should not be negative because 0 K is absolute zero. If a conversion gives a negative Kelvin value, the input is below absolute zero and should be checked.

Which temperature scale is used in science? ⌄

Kelvin is the SI base unit for thermodynamic temperature. Celsius is also commonly used in everyday contexts and many scientific settings.

Sources, assumptions and disclaimer

This converter is intended for general calculation, study, cooking reference and everyday planning. Temperature formulas use standard relationships between Celsius, Fahrenheit, Kelvin and other scales. Results are rounded for readability and should be checked against official standards for safety-critical, laboratory, industrial or medical use.

Kelvin: Kelvin is the SI base unit for thermodynamic temperature.
Celsius and Fahrenheit: conversions use the standard offset formulas shown on this page.
Reference temperatures: everyday reference points such as room temperature, boiling water and oven settings are approximate and can vary by pressure, appliance calibration and local conditions.
Cooking and ovens: oven temperatures and gas marks are broad cooking references. Real oven temperatures can vary from the set value.
Health disclaimer: body temperature references are for context only and are not medical advice. If a temperature reading concerns you, use official health guidance or speak to a healthcare professional.