TemperatureConversion Formulas & Examples
Celsius → Fahrenheit
°F = (°C × 1.8) + 32Example: 20°C × 1.8 + 32 = 68°F
Fahrenheit → Celsius
°C = (°F − 32) ÷ 1.8Example: (68°F − 32) ÷ 1.8 = 20°C
Celsius → Kelvin
K = °C + 273.15Example: 25°C + 273.15 = 298.15 K
Kelvin → Celsius
°C = K − 273.15Example: 298.15 K − 273.15 = 25°C
Fahrenheit → Kelvin
K = (°F − 32) ÷ 1.8 + 273.15Example: (77°F − 32) ÷ 1.8 + 273.15 = 298.15 K
Kelvin → Fahrenheit
°F = (K − 273.15) × 1.8 + 32Example: (298.15 K − 273.15) × 1.8 + 32 = 77°F
Temperature Reference Table
| Reference Context | Value 1 | Value 2 | Value 3 |
|---|---|---|---|
| Absolute Zero (Minimum Thermodynamic Kinetic Energy) | 0 K | -273.15°C | -459.67°F |
| Liquid Nitrogen (Cryogenic Storage) | 77.36 K | -195.79°C | -320.42°F |
| Dry Ice Sublimation Point (CO2 Phase Boundary) | 194.65 K | -78.5°C | -109.3°F |
| Scale Convergence Point (Numerical Identity) | 233.15 K | -40°C | -40°F |
| Fahrenheit's Original Brine Zero Calibration | 255.37 K | -17.78°C | 0°F |
| Freezing Point of Pure Water (1 atm) | 273.15 K | 0°C | 32°F |
| Ideal Room Ambient Climate | 293.15 K | 20°C | 68°F |
| Standard Laboratory Ambient (IUPAC STP) | 298.15 K | 25°C | 77°F |
| Normal Human Body Core Baseline | 310.15 K | 37°C | 98.6°F |
| Boiling Point of Pure Water (1 atm) | 373.15 K | 100°C | 212°F |
| Standard Moderate European Baking Oven | 453.15 K | 180°C | 356°F |
| Incandescent Red Hot Steel Glowing | 1000 K | 726.85°C | 1340.33°F |
| Solar Photosphere Outer Surface | 5778 K | 5504.85°C | 9940.73°F |
Frequently Asked Questions
Q.What are the three primary temperature scales used in science and everyday life?
The three primary temperature scales are Celsius (°C), Fahrenheit (°F), and Kelvin (K). Celsius is the global metric everyday standard, Fahrenheit is used primarily in the United States for weather and domestic cooking, and Kelvin is the official SI thermodynamic base unit used in physics, chemistry, and astronomy.
Q.What is the formula to convert Celsius to Fahrenheit and vice versa?
To convert Celsius to Fahrenheit, multiply by 1.8 and add 32: °F = (°C × 1.8) + 32. To convert Fahrenheit to Celsius, subtract 32 and divide by 1.8: °C = (°F − 32) ÷ 1.8. You can use our dedicated Celsius to Fahrenheit and Fahrenheit to Celsius converters for instant calculations.
Q.Why does the Kelvin scale not use a degree symbol?
Kelvin is an absolute thermodynamic measurement unit rather than a calibrated scale position relative to arbitrary fluid properties. By international metrological agreement established in 1967 at the 13th General Conference on Weights and Measures (CGPM), it is written simply as K (e.g., 298.15 K), not °K.
Q.At what temperature do Celsius and Fahrenheit have the same numerical value?
Celsius and Fahrenheit intersect at exactly −40 degrees: −40°C = −40°F. Because the scales have different zero points and different interval sizes, this is the unique convergence point where both thermometers show identical numbers.
Q.What is absolute zero, and can temperature drop below it?
Absolute zero is 0 K (−273.15°C or −459.67°F). It represents the fundamental thermodynamic ground state where entropy reaches its theoretical minimum and classical molecular kinetic motion ceases. In natural physical states, temperature cannot fall below 0 K.
Q.Which countries still officially use the Fahrenheit scale today?
The Fahrenheit scale remains the official legal standard for weather reporting, domestic thermostats, and cooking in the United States and its territories (Puerto Rico, Guam, US Virgin Islands), as well as the Bahamas, Belize, the Cayman Islands, and Palau.