Temperature Converter

Fahrenheit → Celsius: °C = (°F − 32) × 5/9. Celsius → Fahrenheit: °F = (°C × 9/5) + 32. Celsius → Kelvin: K = °C + 273.15. Kelvin → Celsius: °C = K − 273.15.

−40° is the only point where Fahrenheit and Celsius read the same number. Above that, Fahrenheit values grow faster than Celsius values; below it, the reverse.

The most common baking temperatures, rounded the way recipes actually use them: 275 °F = 135 °C (gas mark 1, slow oven), 325 °F = 163 °C (gas mark 3), 350 °F = 177 °C (gas mark 4 — the default for cakes and cookies), 375 °F = 191 °C (gas mark 5), 400 °F = 204 °C (gas mark 6 — roasting), 425 °F = 218 °C (gas mark 7), 450 °F = 232 °C (gas mark 8 — pizza), 475 °F = 246 °C (gas mark 9 — very hot).

Convection / fan-forced ovens cook faster. The standard rule is to drop the temperature by 25 °F (about 15 °C), or keep the same temperature and shorten the time by ~25%.

At standard atmospheric pressure (sea level, 1 atm): water freezes at 0 °C = 32 °F = 273.15 K, and boils at 100 °C = 212 °F = 373.15 K.

Boiling point drops by roughly 1 °C per 285 m (about 1 °F per 500 ft) of elevation. In Denver (1,609 m / 5,280 ft) water boils near 95 °C (203 °F); on Everest's summit it boils around 70 °C (158 °F) — which is why high-altitude baking and pasta cooking need adjusted times.

Normal human body temperature is around 37 °C = 98.6 °F. Fever is generally defined as ≥ 38 °C (100.4 °F). Hypothermia begins below 35 °C (95 °F).

Useful weather reference points: 0 °C / 32 °F (water freezes), 10 °C / 50 °F (jacket weather), 20 °C / 68 °F (room temperature), 30 °C / 86 °F (hot summer day), 40 °C / 104 °F (heatwave). A quick mental shortcut: double the Celsius value and add 30 to estimate Fahrenheit (accurate to within a few degrees in the everyday weather range).

Kelvin is the SI base unit of temperature. It uses the same degree size as Celsius but starts at absolute zero — the theoretical lowest temperature, where all classical molecular motion stops. Absolute zero = 0 K = −273.15 °C = −459.67 °F.

Because Kelvin has no negative numbers, it's the standard for physics, chemistry, astronomy, and engineering. Room temperature is roughly 293–298 K. The cosmic microwave background is about 2.7 K. The surface of the Sun is around 5,778 K.