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Temperature Converter

Celsius, Fahrenheit, Kelvin, Rankine — all in one shot.

Temperature conversion is one of the most common calculations for travellers, cooks, engineers, and scientists. Celsius and Fahrenheit are the everyday scales; Kelvin and Rankine are for science and engineering. This converter handles all four at once.

25 °C equals
77 °F
ScaleValue
Fahrenheit77 °F
Kelvin298.15 K
Rankine536.67 °R

Celsius vs Fahrenheit: The History

Celsius (°C) was proposed by Swedish astronomer Anders Celsius in 1742 and is now the official scale for most of the world. Fahrenheit (°F) was developed by German physicist Daniel Gabriel Fahrenheit in 1724 and remains the everyday standard in the US, its territories, and the Cayman Islands.

  • Water freezes: 0 °C = 32 °F
  • Body temperature: 37 °C = 98.6 °F
  • Water boils: 100 °C = 212 °F
  • The single point where they're equal: −40 °C = −40 °F

Quick Reference: Common Temperatures

The temperatures most people actually need to convert:

  • Oven temperatures: 180 °C = 356 °F; 200 °C = 392 °F; 220 °C = 428 °F
  • Fridge: 4 °C = 39 °F; freezer: −18 °C = 0 °F
  • Comfortable room: 20-22 °C = 68-72 °F
  • Hot summer day: 35 °C = 95 °F; heat wave: 40 °C = 104 °F
  • Mild winter: −5 °C = 23 °F; bitter cold: −20 °C = −4 °F
  • Human fever: 38.5 °C = 101.3 °F; serious fever: 40 °C = 104 °F

Kelvin and Absolute Zero

Kelvin is the thermodynamic temperature scale used in science. Unlike Celsius and Fahrenheit, Kelvin has no negative values — 0 K is absolute zero, the lowest possible temperature where particles have minimum kinetic energy.

  • Absolute zero: 0 K = −273.15 °C = −459.67 °F
  • 0 °C = 273.15 K
  • 100 °C = 373.15 K
  • Surface of the sun: ~5,778 K
  • Liquid nitrogen: 77 K = −196 °C
  • Liquid helium: 4.2 K = −268.95 °C

How to Convert Temperature

Two steps to convert between any temperature scales.

  1. 1
    Enter the temperature and select the scale
    Type your temperature value and choose Celsius, Fahrenheit, Kelvin, or Rankine from the dropdown.
  2. 2
    Read all conversions
    The table shows every scale simultaneously. The primary result shows the most common conversion for your input (°C → °F or vice versa).

FAQ

How do I convert Celsius to Fahrenheit?
°F = °C × 9/5 + 32. Example: 25 °C = 77 °F.
How do I convert Fahrenheit to Celsius?
°C = (°F − 32) × 5/9. Example: 100 °F ≈ 37.78 °C.
At what temperature are Celsius and Fahrenheit equal?
At −40°. It's the only point where the two scales give the same number.
What is Kelvin used for?
Kelvin is the SI base unit for thermodynamic temperature used in physics, chemistry, and engineering. 0 K is absolute zero (the lowest possible temperature; −273.15 °C). You can't have negative Kelvin.
What is Rankine?
Rankine uses the Fahrenheit degree size but starts at absolute zero (like Kelvin). Used in some US engineering fields. 0 °R = 0 K = −273.15 °C = −459.67 °F.

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