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Quick guide
Understand the calculation
Convert absolute temperatures across eight scales —Celsius, Fahrenheit, Kelvin, Rankine, Réaumur, Delisle, Newton and Rømer— and temperature differences across the seven scales that increase in the same direction. The tool shows the substituted calculation and, on demand, every available equivalent.
When to use this tool
Use it to translate an experimental or environmental condition among °C, °F and K; read engineering documentation that uses °R; compare reference points written in historical scales; or convert a temperature change for heat capacities, expansion coefficients and thermal balances. Choose “Difference” when the amount of change matters rather than the initial reading.
How values and differences are converted
In “Temperature”, the value is first expressed in kelvin and then converted to the other scale, so both degree size and zero-point position matter. In “Difference”, zero-point offsets are not carried across: only the ratio between degree sizes applies, so Δ1 °C = Δ1 K = Δ1.8 °F = Δ1.8 °R. The displayed operation uses the entered value. Swapping scales reverses the conversion without changing that value, and the optional table shows it in every available scale.
“Temperature” rejects values below 0 K —for Delisle, values above 559.725 °De— and input must be a finite decimal, optionally in scientific notation. Delisle is omitted from “Difference” because its scale increases as temperature falls, so a positive difference would run opposite to the other seven. The tool converts scales; it does not correct instrument calibration, estimate uncertainty, model heat transfer, or determine a substance's temperature at a given pressure.
Verified examples
- Room temperature · 25 °C
25 °C = 298.15 K = 77 °F - Temperature increase · Δ10 °C
Δ10 °C = Δ10 K = Δ18 °F = Δ18 °R - Water boiling point · 80 °Ré
80 °Ré = 100 °C = 373.15 K = 0 °De
Frequently asked questions
Is a 1 °C difference equal to a 1 K difference?
Yes. Celsius and kelvin use the same degree size, so a change of 1 °C is a change of 1 K. Their absolute values differ by 273.15 because their zero points do not coincide.
Why is Δ10 °C equal to Δ18 °F rather than 50 °F?
A difference does not carry the 32-degree offset from the absolute formula. Only the 9/5 scale factor applies: 10 × 9/5 = 18.
Why is Delisle missing from difference mode?
The Delisle scale is inverted: its number increases as temperature falls. This tool avoids mixing that sign convention with the seven scales that increase in the same direction; Delisle remains available for absolute temperatures.