Temperature Interval Converter
Convert temperature differences (intervals). Unlike absolute temperature, intervals scale linearly.
Written by Rahman · Last reviewed
Quick answer
A temperature interval is a difference rather than a position on a scale, so no offset is applied. An interval of one kelvin equals one degree Celsius exactly, while one degree Fahrenheit is 5/9 of a kelvin, or 0.5556. This is why a 10 °C rise is an 18 °F rise even though 10 °C and 18 °F are entirely different temperatures.
| Kelvin (K) | 1 |
| Degree Celsius (°C) | 1 |
| Degree Fahrenheit (°F) | 1.8 |
| Degree Rankine (°R) | 1.8 |
| Degree Réaumur (°Ré) | 0.8 |
About the Temperature Interval Converter
A temperature interval is a difference between two temperatures, not an absolute temperature. Unlike absolute readings, intervals scale linearly, so a change of 1°C equals a change of 1 K exactly.
This converter is used in engineering and science whenever a temperature change or range (rather than a fixed point) must be expressed in different scales.
Why an interval needs its own converter
Converting a temperature reading requires two operations: a scale change and an offset, because Celsius and Fahrenheit place their zero points differently. Converting a temperature difference requires only the scale change, because the offsets cancel when one reading is subtracted from another.
That is the whole reason this page exists separately. A reading of 20°C is 68°F, but a rise of 20°C is a rise of 36°F. Running an interval through the ordinary temperature formula adds an offset that does not belong there and inflates the answer substantially.
- An interval of 1°C equals an interval of 1 K exactly, which is why kelvin and Celsius intervals are interchangeable even though the readings are not.
- An interval of 1°F equals an interval of 1 degree Rankine, for the same reason.
- The Celsius-to-Fahrenheit interval factor is simply 9/5, with no addition of 32.
Where the distinction shows up in practice
Anything expressed as a difference, a range, a tolerance or a rate is an interval rather than a reading, and these appear more often than people expect.
Thermal expansion coefficients are quoted per degree. Specific heat capacities are energy per unit mass per degree. Temperature rise across a heatsink, the differential a thermostat operates over, and the daily range in a weather report are all intervals. In every case the offset must be left out.
- A tolerance of ±5°C is ±9°F, not ±41°F.
- A rate of 2°C per hour is 3.6°F per hour.
- If the quantity has "per degree", "difference", "rise", "range" or "±" attached to it, it belongs on this page rather than the temperature converter.
Frequently Asked Questions
How is a temperature interval different from a temperature?
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A temperature is a fixed point on a scale; an interval is the gap between two temperatures. Intervals convert by simple multiplication, while absolute temperatures need offset formulas.
Is a 1°C interval the same as a 1 K interval?
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Yes. The Celsius and Kelvin scales have the same step size, so an interval of 1°C equals an interval of 1 K.
How do Celsius and Fahrenheit intervals compare?
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A change of 1°C equals a change of 1.8°F, because the Fahrenheit degree is smaller.