Celsius Converter — °C to Fahrenheit, Kelvin & Rankine
Enter any temperature in Celsius and instantly see the equivalent in Fahrenheit, Kelvin and Rankine — with a visual scale showing key reference points.
°C
°F = °C × 9/5 + 32
- 1
°C × 9÷5 (scale)
25 × (9÷5) = 45 - 2
Fahrenheit = scaled + 32
45 + 32 = 77
How does this calculator work?
Multiply Celsius by 9/5 and add 32 to get Fahrenheit. Add 273.15 to get Kelvin. The scales meet at −40 (−40 °C = −40 °F). Key reference points: 0 °C = 32 °F (freezing), 37 °C = 98.6 °F (body temp), 100 °C = 212 °F (boiling). All conversions are exact definitions, not approximations.
Formula
How this is calculated
The Celsius scale is the world's most widely used temperature scale in everyday life and science. Its two defining reference points are the freezing point of pure water (0 °C) and its boiling point (100 °C) at standard atmospheric pressure. Converting to Fahrenheit requires multiplying by the scale factor 9/5 (because one Celsius degree equals 9/5 of a Fahrenheit degree) and then adding 32 to shift the zero point.
Kelvin is the SI unit of thermodynamic temperature. It uses the same degree size as Celsius but starts at absolute zero — the coldest possible temperature — which is −273.15 °C. Adding 273.15 to any Celsius value gives Kelvin directly. Rankine is the absolute scale that uses Fahrenheit-sized degrees: it shares the same zero as Kelvin but each step is the smaller Fahrenheit degree, so °R = K × 9/5.
All conversions are exact mathematical definitions — no measured constants enter the calculation. The only source of imprecision is display rounding, shown here to four decimal places.
Frequently asked questions
100 °C equals 212 °F — the boiling point of water at sea level. The conversion is 100 × 9/5 + 32 = 180 + 32 = 212 °F.
The two scales meet at −40 degrees: −40 °C equals exactly −40 °F. This is the only crossover point.
The kelvin (symbol K, no degree sign) is an SI base unit of temperature rather than a degree-based scale. Its magnitude matches one Celsius degree, but because it starts at absolute zero, temperatures are expressed as plain kelvins, not "degrees Kelvin".
Also known as
TG we-Calculate Editorial Team. (2026). Celsius Converter — °C to Fahrenheit, Kelvin & Rankine [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/celsius-converter
TG we-Calculate Editorial Team. "Celsius Converter — °C to Fahrenheit, Kelvin & Rankine." TG we-Calculate. 2026. https://we-calculate.com/calculator/celsius-converter.
TG we-Calculate Editorial Team, "Celsius Converter — °C to Fahrenheit, Kelvin & Rankine," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/celsius-converter
@misc{wecalculate_celsius_converter, title = {Celsius Converter — °C to Fahrenheit, Kelvin & Rankine}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/celsius-converter}}, year = {2026}, note = {TG we-Calculate} }
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