Temperature Converter

Temperature measures the average kinetic energy of particles in a system, with several scales used worldwide: Celsius (°C) is the global everyday standard; Fahrenheit (°F) is American everyday usage; Kelvin (K) is the SI absolute scale used in science; Rankine (°R) is the absolute version of Fahrenheit used in some American engineering. Unlike other unit categories, temperature scales differ in both their zero points and their degree sizes, so conversion uses formulas — not simple multiplication. The relationship between Celsius and Fahrenheit is °F = (°C × 9/5) + 32, and between Celsius and Kelvin is K = °C + 273.15. Reference points: water freezes at 0°C / 32°F / 273.15 K, water boils at 100°C / 212°F / 373.15 K, absolute zero is −273.15°C / −459.67°F / 0 K. Use temperature conversion for weather forecasts, cooking, medical diagnostics, scientific research, and HVAC engineering.

Celsius is the global temperature standard for weather, science, and daily life outside the United States.

Fahrenheit is the everyday temperature scale in the United States, used for weather, cooking, and body temperature.

The Kelvin is the SI thermodynamic temperature scale, starting at absolute zero and used in all scientific work.

The Rankine scale is the absolute version of Fahrenheit, used in American engineering thermodynamics calculations.

• ✓Water freezes at 0 °C = 32 °F = 273.15 K. Water boils at 100 °C = 212 °F = 373.15 K at standard pressure.
• ✓Kelvin is the SI unit with zero at absolute zero (coldest possible temperature). Unlike C and F, Kelvin values are never negative.
• ✓The quick mental conversion: °F ≈ 2 × °C + 30. At 20 °C this gives 70 °F (actual: 68 °F — close enough for daily weather).
• ✓Human body core temperature: 37.0 °C = 98.6 °F. Fever starts at 38.0 °C = 100.4 °F.

• ✗Forgetting that temperature conversion is not just multiplication — the offset (273.15 for K, 32 for F) matters.
• ✗Confusing degrees Celsius (°C) with degrees of temperature change. A rise of 5 °C equals a rise of 9 °F.
• ✗Reading a US weather forecast as Celsius — 90 °F is warm (32 °C), not freezing.
• ✗Using Kelvin below zero — absolute zero (0 K) is the minimum, there is no negative Kelvin.