Temperature Converter

Convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K) with an interactive visual thermometer gauge, textbook mathematical fraction formulas, and physical thermodynamic reference points.

Temperature Input

°C
Converted Temperature
212 °F(from 100 °C)
Extreme Heat / Boiling

Celsius

100°C

Fahrenheit

212°F

Kelvin

373.15 K

Dynamic Thermal Spectrum Gauge

Relative temperature position between freezing (-20°C) and boiling (120°C)

-20°C (-4°F)0°C (32°F)37°C (98.6°F)100°C (212°F)
Mathematical Conversion Formula

(100°C × 9/5) + 32 = 212°F

Physical Landmark Temperature Benchmarks
BenchmarkCelsiusFahrenheitKelvin
Absolute Zero-273.15°C-459.67°F0 K
Dry Ice Sublimation-78.5°C-109.3°F194.65 K
Freezing Point of Water0°C32°F273.15 K
Standard Room Temperature21°C69.8°F294.15 K
Human Body Temperature37°C98.6°F310.15 K
Boiling Point of Water100°C212°F373.15 K

The Physics of Temperature Measurement

Temperature is an objective quantitative measure of the average kinetic energy of the particles within a substance. Unlike length or mass where zero represents the complete absence of matter, temperature scales historically established different arbitrary zero-points based on observable natural phenomena (such as the freezing point of brine or pure water).

1. Celsius to Fahrenheit Formula
°F=( °C ×
95
) + 32
2. Fahrenheit to Celsius Formula
°C=( °F - 32 ) ×
59
3. Celsius to Kelvin (Absolute Thermodynamic Scale)
K = °C + 273.15
Step-by-Step Conversion Examples
Example 1: Converting 100°C to Fahrenheit (Water Boiling Point)
°F=( 100 ×
95
) + 32=180 + 32=212°F
Example 2: Converting 68°F to Celsius (Standard Room Temperature)
°C=( 68 - 32 ) ×
59
=36 ×
59
=20°C

Detailed Comparison of the Three Major Temperature Scales

  • Celsius (°C): Developed by Swedish astronomer Anders Celsius in 1742. It sets 0°C at the freezing point of water and 100°C at the boiling point under standard atmospheric pressure (1 atm). It is the official temperature unit used across virtually every country worldwide for meteorology, science, and everyday life.
  • Fahrenheit (°F):Proposed by physicist Daniel Gabriel Fahrenheit in 1724. It sets 32°F at water's freezing point and 212°F at water's boiling point, creating exactly 180 degrees of separation between the two phase transitions. Fahrenheit provides finer gradations for human atmospheric perception (e.g. 0°F is dangerously cold, 100°F is very hot).
  • Kelvin (K): Named after physicist Lord Kelvin. It is the base unit of thermodynamic temperature in the International System of Units (SI). Absolute zero (0 K) represents the state where particles have minimum thermodynamic heat energy. Unlike Celsius and Fahrenheit, Kelvin does not use the degree symbol (°).

Mental Conversion Shortcuts for Everyday Life

  • Quick °C to °F Approximation: Multiply the Celsius number by 2 and add 30 (e.g. 20°C × 2 + 30 = 70°F; exact is 68°F).
  • Quick °F to °C Approximation: Subtract 30 from the Fahrenheit number and divide by 2 (e.g. (70°F - 30) ÷ 2 = 20°C; exact is 21.1°C).
  • The Exact Equal Point: Celsius and Fahrenheit intersect exactly at -40° (-40°C = -40°F).

Frequently Asked Questions

What is the difference between Celsius and Fahrenheit?
Celsius and Fahrenheit use different zero points and degrees of spacing. Water freezes at 0°C (32°F) and boils at 100°C (212°F). A 1-degree change in Celsius equals 1.8 degrees in Fahrenheit.
Why does Kelvin not have degree symbols?
Kelvin is an absolute thermodynamic temperature scale rather than a relative scale. Therefore, temperatures in Kelvin are written simply as 'K' (e.g. 300 K), not '°K'.
At what temperature are Celsius and Fahrenheit equal?
Celsius and Fahrenheit are exactly equal at -40 degrees (-40°C = -40°F).

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