History & Background
Daniel Gabriel Fahrenheit invented his scale in 1724 with 0 °F at the freezing point of brine and 96 °F at human body temperature. Anders Celsius proposed his scale in 1742 — though originally inverted, with 0 at the boiling point of water. William Thomson (Lord Kelvin) defined the absolute scale in 1848, anchored at absolute zero.
Conversion Formulas
°F = °C × 9/5 + 32°C = (°F − 32) × 5/9K = °C + 273.15°C = K − 273.15°F = K × 9/5 − 459.67
Common Values
- 0 °C = 32 °F = 273.15 K (water freezes)
- 100 °C = 212 °F = 373.15 K (water boils)
- 37 °C = 98.6 °F (body temperature)
- 20 °C = 68 °F (room temperature)
- −40 °C = −40 °F (the only point where they are equal)
- 180 °C = 356 °F (oven, baking)
Common Uses
- Cooking and baking with US recipes (oven temperature)
- Medical fever readings
- Travel weather forecasts
- Science homework and lab reports
- HVAC and refrigeration settings
Frequently Asked Questions
What is 100 F in Celsius?
(100 − 32) × 5/9 = 37.78 °C — borderline fever.
What is 180 °C in Fahrenheit?
180 × 9/5 + 32 = 356 °F — moderate baking heat.
Why is 0 K = absolute zero?
It is the temperature where molecular motion stops. Equivalent to −273.15 °C or −459.67 °F.
Are Celsius and centigrade the same?
Yes — "centigrade" was renamed Celsius in 1948 to avoid confusion with the angular unit.
Why does the US still use Fahrenheit?
Historical inertia. The US adopted Fahrenheit in the 1700s and never officially metricated weather forecasts.