Temperature Interval Converter

A temperature interval describes the *size* of a temperature change, not an absolute reading — the distinction matters because converting an interval between scales is mathematically simpler than converting an absolute temperature. Converting an absolute temperature (like "20°C") to Fahrenheit requires both scaling and an offset (°F = °C × 1.8 + 32), but converting a temperature *change* (like "a rise of 20°C") only requires the scaling factor, since the offset cancels out when you're measuring a difference rather than a fixed point.

Our Temperature Interval converter supports kelvin (the SI base unit, and numerically identical in interval size to Celsius), degree Celsius and degree centigrade (the same scale under two names), degree Fahrenheit, degree Rankine (the Fahrenheit-scaled absolute temperature scale, matching Fahrenheit's degree size), and degree Réaumur (an older European scale still occasionally seen in historical and specialized references). A Celsius or Kelvin interval is exactly 1.8 times the size of the equivalent Fahrenheit or Rankine interval, and exactly 0.8 times the size of a Réaumur interval.

To use the converter, select your starting and target units from the dropdown lists and enter a value — the result is calculated instantly to up to 12 significant digits. For example, converting a 10°C temperature rise to Fahrenheit gives 18°F — note this is different from converting an absolute reading of 10°C, which would be 50°F.

Temperature interval conversions are essential wherever a calculation depends on a change in temperature rather than an absolute value: thermal expansion calculations (how much a material's dimensions change per degree of temperature swing), heat transfer equations (the driving force for heat flow is a temperature difference, ΔT), specific heat capacity calculations (energy required per degree of temperature rise), and HVAC load calculations (indoor-outdoor temperature differences drive heating and cooling demand). Getting interval conversions right — rather than mistakenly applying the absolute-temperature formula with its offset — is a common source of error for students and engineers first working across unit systems.

All conversion factors used in this tool reflect the precise, standard degree-size relationships between the five temperature scales, so results are dependable for thermal engineering calculations, physics coursework, and technical documentation. The converter is free, requires no account, and works equally well on desktop and mobile devices.

Temperature interval values also feed directly into the Thermal Expansion converter elsewhere in this section, since expansion coefficients are defined per degree of temperature change — converting an interval correctly here is often the first step before applying it to an expansion, resistance, or specific heat calculation that spans multiple unit systems.