Constants Database

Comprehensive reference for mathematical, physical and chemical constants

Name Symbol Value Unit Category

Constant Name

c
299792458
m/s
Physics
The speed of light in vacuum is a universal physical constant important in many areas of physics. Its exact value is 299,792,458 metres per second.
The speed of light was first measured by Ole Rømer in 1676. It is now defined as exactly 299,792,458 m/s since 1983.
Applications
  • Special relativity
  • Electromagnetism
  • Quantum mechanics
  • Astronomy and cosmology
  • GPS technology
Related Constants
Mathematical Constants
15 constants

Fundamental constants in mathematics, often arising in analysis, number theory, and geometry.

Physical Constants
22 constants

Universal constants that appear in physical theories and equations.

Chemical Constants
12 constants

Constants used in chemistry, thermodynamics, and material science.

Universal Constants
7 constants

Fundamental constants that define our universe and its properties.

Astronomical Constants
8 constants

Constants used in astronomy, astrophysics, and cosmology.

What are Physical Constants?

Physical constants are fundamental invariant quantities that appear in the basic theoretical equations of physics. They are not derived from other constants and are considered universal in nature.

Key characteristics:

In 2019, the SI system was redefined based on fixed values of seven defining constants:

  1. Speed of light in vacuum (c)
  2. Planck constant (h)
  3. Elementary charge (e)
  4. Boltzmann constant (k)
  5. Avogadro constant (NA)
  6. Hyperfine transition frequency of Cs (ΔνCs)
  7. Luminous efficacy (Kcd)

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