Temperature Converter
Choose the scale you have and the scale you need, then type the temperature. The converter runs the workbook formulas between Celsius, Fahrenheit and kelvin — the only conversions on the site that add rather than multiply.
Temperature
What this calculates
Temperature is the one quantity here that does not convert by a single factor, because the scales start from different zeros. Celsius sets zero at the freezing point of water, Fahrenheit at thirty-two degrees below it, and kelvin at absolute zero, 273.15 degrees below. Converting means shifting as well as scaling, and it is easy to do half the job in your head. This page does the whole of it.
Metal work meets all three scales. Service temperatures for a facade or a pipe run are stated in Celsius on Saudi projects and in Fahrenheit on American specifications; heat treatment temperatures on a mill certificate come in either; creep and cryogenic data in standards are often tabulated in kelvin. A datasheet that quotes a property at 68 °F is quoting it at 20 °C, room temperature, and this page shows that at a glance.
A temperature and a temperature difference are different things, and only the first needs this converter. A change of fifty degrees Celsius is a change of fifty kelvin and of ninety degrees Fahrenheit — the offset drops out of a difference. The thermal expansion calculator takes a difference, so give it the °C change directly; do not run the two end temperatures through here and subtract the Fahrenheit figures.
Show the formula and a worked example
The formula
- °F = °C × 9/5 + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
Dimensions in millimetres, density ρ in kg/m³ — as the engine runs them.
°F = °C × 9/5 + 32 and °C = (°F − 32) × 5/9 are the workbook's two Fahrenheit rows, one for each direction. K = °C + 273.15 is the kelvin row; the converter runs it backwards as °C = K − 273.15 and marks that result as run backwards. The workbook has no Fahrenheit-to-kelvin row, so that pair is refused: convert to Celsius first, then to kelvin.
Negative temperatures are accepted, since Celsius and Fahrenheit both go below zero. The formulas are exact by definition; only your input limits the precision.
Worked example
| Quantity | Temperature |
|---|---|
| Value | 20 °C |
| To | °F |
| Theoretical result | 68 °F |
Computed by the calculation engine from these inputs at render time, rounded only for display.
Frequently asked
- 01Why can I not convert °F straight to K?
- Because the workbook carries no row for that pair, and the converter runs only the rows it carries. Convert Fahrenheit to Celsius, then Celsius to kelvin — two steps, both exact.
- 02Is a difference of 50 °C the same as a difference of 50 K?
- Yes. The two scales have the same size of degree and differ only in where zero sits, so a change is identical in both. In Fahrenheit the same change is 90 degrees, because a Fahrenheit degree is five-ninths the size.
- 03What temperature does a datasheet mean by "room temperature"?
- Usually 20 °C, sometimes 23 or 25 °C; American documents say 68 °F, 73 °F or 77 °F for the same three. Mechanical properties are quoted there unless the datasheet gives a range, and the thermal expansion coefficient is a mean from there up to the range's upper temperature.