Temperature Converter
Convert between different temperature scales with precision. Celsius, Fahrenheit, Kelvin, and Rankine - all covered.
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The History of Temperature Measurement
Early Thermometers (1592)
Galileo Galilei invented the first thermometer using air expansion:
- Air thermometer: Based on gas expansion
- Relative scale: No fixed reference points
- Qualitative: Hotter/colder measurements
- Inconsistent: Affected by atmospheric pressure
Fahrenheit Scale (1724)
Daniel Gabriel Fahrenheit's mercury thermometer:
- Body temperature: Set at 96°F (later adjusted)
- Freezing brine: 0°F (later adjusted to 32°F)
- Mercury: More consistent than air
- Popular in: English-speaking countries
Celsius Scale (1742)
Anders Celsius's centigrade scale:
- Boiling water: 0°C (later reversed)
- Freezing water: 100°C (later 0°C)
- Decimal system: 100 equal divisions
- Scientific: Easy mathematical relationships
Kelvin Scale (1848)
William Thomson (Lord Kelvin) created absolute scale:
- Absolute zero: -273.15°C = 0 K
- Thermodynamic: Based on heat energy
- SI unit: Official temperature unit
- Scientific: Used in physics and chemistry
Understanding Temperature Scales
Celsius (°C)
The Celsius scale is a temperature scale based on 0° for the freezing point of water and 100° for the boiling point of water at 1 atm pressure.
Boiling point: 100°C
Human body: ~37°C
Room temperature: ~20-25°C
Fahrenheit (°F)
The Fahrenheit scale is a temperature scale based on 32° for the freezing point of water and 212° for the boiling point of water at 1 atm pressure.
Boiling point: 212°F
Human body: 98.6°F
Room temperature: 68-77°F
Kelvin (K)
The Kelvin scale is an absolute thermodynamic temperature scale where absolute zero is 0 K and the freezing point of water is 273.15 K.
Freezing point: 273.15 K
Boiling point: 373.15 K
No negative values possible
Rankine (°R)
The Rankine scale is an absolute scale of thermodynamic temperature named after William John Macquorn Rankine, similar to Kelvin but in Fahrenheit degrees.
Freezing point: 491.67°R
Boiling point: 671.67°R
Used in engineering calculations
Temperature in Everyday Life
Home & Cooking
- • Oven temperature: °F/°C
- • Refrigerator: 4°C (39°F)
- • Freezer: -18°C (0°F)
- • Room temperature: 20-25°C
Weather & Climate
- • Daily weather: °C or °F
- • Climate records: long-term data
- • Wind chill: combined factors
- • Heat index: humidity effects
Health & Medicine
- • Body temperature: 37°C (98.6°F)
- • Fever threshold: 38°C (100.4°F)
- • Medical equipment: precise control
- • Vaccine storage: -80°C
Industry & Manufacturing
- • Metal melting: 1000+°C
- • Chemical reactions: controlled temperatures
- • Food processing: pasteurization
- • Electronics: component limits
Science & Research
- • Absolute zero experiments: ~0 K
- • Superconductivity: very low temperatures
- • Plasma physics: millions of °C
- • Space temperatures: -270°C to 5500°C
Global Standards
- • Science: Kelvin (SI unit)
- • Most countries: Celsius
- • USA: Fahrenheit common
- • Aviation: Celsius
Common Temperature Conversions
0°C (Freezing) =
- 32°F
- 273.15 K
- 491.67°R
100°C (Boiling) =
- 212°F
- 373.15 K
- 671.67°R
20°C (Room Temp) =
- 68°F
- 293.15 K
- 527.67°R
37°C (Body Temp) =
- 98.6°F
- 310.15 K
- 558.27°R
-40°C =
- -40°F
- 233.15 K
- 419.67°R
Absolute Zero =
- -273.15°C
- -459.67°F
- 0°R