Temperature Interval converter
A difference in temperature, not a point on a scale: a 10 °C rise is a 18 °F rise, with no 32-degree offset involved.
Converter
Quick pairs
tap to loadOne degree celsius in every temperature interval unit
6 rows| Unit | Symbol | 1 °C equals |
|---|---|---|
| Kelvin | K | 1 |
| Degree Fahrenheit | °F | 1.8 |
| Degree Rankine | °R | 1.8 |
| Degree Réaumur | °Ré | 0.8 |
| Millikelvin | mK | 1,000 |
| Microkelvin | µK | 1,000,000 |
How the degree celsius to degree fahrenheit conversion works
Temperature interval units measure a change or difference in temperature, not a point on a scale, and every unit here is sized against the kelvin. A 1-kelvin step and a 1-degree-Celsius step are identical in size (factor 1), which is why Celsius and Kelvin convert one-to-one for intervals even though their zero points differ by 273.15. Degree Fahrenheit and degree Rankine intervals are each 5/9 (0.5555555556) of a kelvin, since the Fahrenheit scale packs 180 degrees into the same span that Celsius covers in 100. Degree Réaumur runs the other way, at 1.25 kelvin per degree, because the old Réaumur scale divided freezing-to-boiling into just 80 degrees instead of 100.
The everyday conversion is degree Celsius to degree Fahrenheit: °F = °C × 1.8. Going back, divide by 1.8 (equivalently, multiply by 0.5555555556). The same 1.8 factor applies to a kelvin interval, since kelvin and Celsius intervals are equal in size.
A 25 °C day-to-night swing works out to 25 × 1.8 = 45 °F of swing. In a lab log recording a 3 K drop inside a cold bath, that's 3 × 1.8 = 5.4 °F. And a 4 °Ré change on an old brewer's thermometer equals 4 × 1.25 = 5 K (which is also 5 °C, since those two intervals match degree for degree).
Interval conversions matter anywhere a change is reported rather than a reading: a thermostat's dead-band, a material's rated operating range, a weather forecast's day-to-night swing, or a process alarm set to trip on a 10-degree rise. Millikelvin and microkelvin intervals show up in physics labs running dilution refrigerators and laser-cooled atom traps, where researchers care about shaving fractions of a degree off an already near-absolute-zero system, not about the absolute reading itself.
The classic mix-up is treating an interval conversion like a point conversion. Converting a Celsius reading to Fahrenheit needs the familiar °F = °C × 1.8 + 32, with that 32-degree offset for the different zero points. Converting a Celsius interval (a rise, a drop, a tolerance band) uses only the 1.8 multiplier — no offset — because the offset cancels out when you subtract two readings. Mixing the two up is an easy way to get a spec sheet's tolerance wrong by 32 degrees.
Questions
How many degree Fahrenheit intervals equal one degree Celsius interval?
A 1 degree Celsius change equals exactly 1.8 degree Fahrenheit change (9/5). This differs from converting a single temperature reading, which also needs the +32 offset.
Which units does this temperature interval converter cover?
7 units, all sized against the kelvin: kelvin, degree Celsius, degree Fahrenheit, degree Rankine, degree Réaumur, millikelvin, and microkelvin. Pick any two from the dropdown lists to convert between them.
Why do some interval conversions come out as repeating decimals?
Fahrenheit and Rankine intervals are exactly 5/9 of a kelvin, a fraction that never terminates in decimal form (0.55555...). The calculator carries enough digits internally that rounding only shows up in the last decimal place of the displayed result.
When would I convert in kelvin instead of degree Celsius?
For interval math the two are interchangeable since both equal 1 kelvin per degree — use Celsius for everyday readability and kelvin when the rest of your calculation (e.g. an ideal-gas or radiation formula) is already in kelvin, which avoids a unit-mismatch error.
Is the degree Réaumur still used anywhere?
Rarely, but it survives in a few traditional cheese- and jam-making recipes and some older European dairy and alcohol-distillation references, where temperatures were historically logged on an 80-degree freezing-to-boiling scale instead of Celsius's 100.
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