Temperature is a physical quantity measuring the degree of heat or cold in an object. Microscopically, it reflects the intensity of molecular thermal motion. Temperature cannot be measured directly; it is inferred from physical properties that change with heat, such as liquid expansion or electrical resistance.
- Celsius (°C) is the global standard for everyday and most industrial use, adopted across Europe, Asia, Africa, South America, Canada, Australia, and New Zealand.
- Fahrenheit (°F) is used primarily in the United States, the Bahamas, Belize, and the Cayman Islands.
- Kelvin (K) is the SI base unit of thermodynamic temperature. Zero Kelvin equals absolute zero, the coldest theoretically possible temperature.1
- Rankine (°R) is an absolute scale using Fahrenheit-sized degree increments, occasionally used in certain legacy engineering fields.
| Convert |
Formula |
Example |
| Celsius to Fahrenheit |
°F = (°C × 9/5) + 32 |
100°C = 212°F |
| Fahrenheit to Celsius |
°C = (°F − 32) × 5/9 |
32°F = 0°C |
| Celsius to Kelvin |
K = °C + 273.15 |
0°C = 273.15 K |
| Kelvin to Celsius |
°C = K − 273.15 |
373.15 K = 100°C |
| Fahrenheit to Kelvin |
K = (°F − 32) × 5/9 + 273.15 |
32°F = 273.15 K |
How to Convert Celsius to Fahrenheit
Multiply the Celsius value by 9/5, then add 32: °F = (°C × 9/5) + 32. For example, 25°C equals 77°F, and 100°C equals 212°F. This conversion is frequently needed in industrial settings where US-manufactured equipment is calibrated in Fahrenheit while internationally calibrated sensors and flow meters use Celsius.
How to Convert Fahrenheit to Celsius
Subtract 32 from the Fahrenheit value, then multiply by 5/9: °C = (°F − 32) × 5/9. For example, 98.6°F equals 37°C. Engineers working across US and international specifications encounter this conversion regularly in process temperature monitoring.
How to Convert Celsius to Kelvin
Add 273.15 to the Celsius value: K = °C + 273.15. For example, 0°C equals 273.15 K, and 100°C equals 373.15 K. Kelvin is the SI base unit for thermodynamic temperature and is used in scientific and industrial calculations where an absolute reference point is required.1
How to Convert Kelvin to Celsius
Subtract 273.15 from the Kelvin value: °C = K − 273.15. For example, 300 K equals 26.85°C. This conversion is common when interpreting laboratory or semiconductor process data reported in Kelvin for practical temperature monitoring in Celsius.
How to Convert Fahrenheit to Kelvin
Subtract 32, multiply by 5/9, then add 273.15: K = (°F − 32) × 5/9 + 273.15. For example, 32°F equals 273.15 K. This is used in thermodynamic engineering calculations where Fahrenheit field readings must feed into equations requiring an absolute temperature scale.