Temperature Scales Guide

Understand Celsius, Fahrenheit, and Kelvin — their origins, reference points, and uses

Overview

Temperature is measured using three main scales: Celsius (C), Fahrenheit (F), and Kelvin (K). Each scale has its own history, reference points, and typical use cases.

Understanding these scales is essential for science, cooking, weather, and international communication.

Celsius (C)

Celsius Scale

Also known as Centigrade

Invented: 1742 by Anders Celsius (Swedish astronomer)

Reference Points:

  • 0C = Freezing point of water
  • 100C = Boiling point of water

Used by: Most of the world for everyday temperature

-40C Extremely cold
0C Water freezes
20-25C Room temperature
37C Body temperature
100C Water boils

Fahrenheit (F)

Fahrenheit Scale

Common in the United States

Invented: 1724 by Daniel Gabriel Fahrenheit (German physicist)

Reference Points:

  • 32F = Freezing point of water
  • 212F = Boiling point of water

Used by: United States, Bahamas, Cayman Islands, Liberia, Palau

-40F Extremely cold
32F Water freezes
68-77F Room temperature
98.6F Body temperature
212F Water boils

Kelvin (K)

Kelvin Scale

The scientific standard

Invented: 1848 by William Thomson (Lord Kelvin)

Reference Points:

  • 0 K = Absolute zero (no molecular motion)
  • 273.15 K = Freezing point of water

Used by: Scientists worldwide, especially in physics and chemistry

0 K Absolute zero
273 K Water freezes
293-298 K Room temperature
310 K Body temperature
373 K Water boils

Note: Kelvin does not use the degree symbol

Conversion Formulas

Celsius to Fahrenheit

F = C x 9/5 + 32 C = (F - 32) x 5/9

Celsius to Kelvin

K = C + 273.15 C = K - 273.15

Fahrenheit to Kelvin

K = (F - 32) x 5/9 + 273.15 F = (K - 273.15) x 9/5 + 32
Fun Fact: -40 is the only temperature that is the same in both Celsius and Fahrenheit!

Related Conversions

Celsius to Fahrenheit Fahrenheit to Celsius Celsius to Kelvin Kelvin to Celsius Fahrenheit to Kelvin

Recommended Guides

Pressure Units Guide Energy Units Guide Time Units Guide Paper Sizes Guide Data Transfer Guide
View All Guides

Ready to Convert?

Use our free conversion tools to convert between any units.

Start Converting