Unlike length, mass, or electrical current, temperature measures the average kinetic energy of molecular particles within a thermodynamic substance. Because different historical scales chose differing reference points for zero, temperature conversions require both scaling factors and affine offsets.
The Four Prominent Temperature Scales
- Celsius ($^circ ext{C}$): Defined relative to the freezing ($0^circ ext{C}$) and boiling ($100^circ ext{C}$) points of water at standard atmospheric pressure.
- Fahrenheit ($^circ ext{F}$): Established by Daniel Gabriel Fahrenheit in 1724; freezing occurs at $32^circ ext{F}$ and boiling at $212^circ ext{F}$, producing a 180-degree interval.
- Kelvin ($ ext{K}$): The SI base unit for thermodynamic temperature, setting absolute zero at $0 ext{ K} (-273.15^circ ext{C})$. Note that Kelvin does not use the degree symbol ($^circ$).
- Rankine ($^circ ext{R}$): The imperial thermodynamic equivalent of Kelvin, setting absolute zero at $0^circ ext{R} (-459.67^circ ext{F})$ with the degree interval matching Fahrenheit.
Universal Conversion Formulas
The standard equations for translating between Celsius and Fahrenheit are:
°F = (°C × 9/5) + 32
°C = (°F – 32) × 5/9
To convert to absolute thermodynamic scales:
K = °C + 273.15
°R = °F + 459.67
Use our interactive temperature converters on Converter For Units for instant calculations with high precision across any scientific or culinary recipe.