Temperature Converter
Convert temperatures between Fahrenheit, Celsius, Kelvin and Rankine, plus the historical Delisle and Newton scales, with the formula shown.
Change the values and press Calculate to work out your own figures.
Enter a temperature, choose its unit and the unit you want. The answer is exact until it is shown, and the same value appears in every other unit.
Show the working
- 98.6 °F = 310.15 K
- 310.15 K = 37 °C
How to use it
Type a temperature, choose the unit it is in and the unit you want, then press Calculate. You can type decimals, fractions such as 3/8, mixed numbers such as 1 1/2, very large or small numbers such as 2.5e6, and simple sums such as 2*3. Swap exchanges the two units.
The answer is worked out exactly and only rounded for display, to 12 significant figures. Below it you get the same value in every other unit on the list, and Show the working gives the conversion factor that was used. Temperatures below absolute zero are refused, because nothing can be colder.
Temperature formulas
Temperature scales differ in both the size of a degree and where zero is, so converting is not a single multiplication. The converter goes through kelvin, the SI unit, and shows both steps.
°C = (°F − 32) × 5/9 °F = °C × 9/5 + 32 K = °C + 273.15 °R = °F + 459.67 = K × 9/5 °De = (100 − °C) × 3/2 °N = °C × 33/100
Readings, not differences
This converter treats every value as a thermometer reading. A change in temperature converts differently: a rise of 10 °C is a rise of 18 °F, while a reading of 10 °C is 50 °F. To convert a difference, multiply by the ratio of degree sizes (9/5 from Celsius to Fahrenheit) and leave the offsets out.
Delisle and Newton
The Delisle and Newton scales are historical, from the 18th century. Delisle counts downwards from the boiling point of water (0 °De) to freezing (150 °De), so higher numbers mean colder. Newton puts freezing at 0 °N and boiling at 33 °N. They appear here for completeness and for history of science work.
Questions
What is 98.6 °F in Celsius?
Exactly 37 °C: (98.6 − 32) × 5/9 = 37.
At what temperature are Fahrenheit and Celsius equal?
At −40 degrees: −40 °C is −40 °F.
What is absolute zero?
0 K, the lowest possible temperature: −273.15 °C or −459.67 °F.
Formulas
result = (value × f(from) + o(from) − o(to)) ÷ f(to)
Sources
Limitations
- Only the units listed are supported here; other temperature units arrive with later M4 slices.
- Temperatures are converted as readings, not as differences (a rise of 10 °C is a rise of 18 °F, not 50 °F).