Physical constants
Search a table of physical and astronomical constants, from the speed of light to the mass of the Sun, and calculate with them straight away using their short names.
Use the names from the last column, such as h, c, qe, NA or G.
Fill in the fields; the answer appears here straight away.
How it's worked out
How it works
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Enter the values
Type the numbers or the formula. Decimals may use a point or a comma. No idea? Click Fill in an example.
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Instant answer
The answer appears as you type, with the most important intermediate values.
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See the working
Under "How it's worked out" you see the steps, handy for checking your own calculation.
Searching
Type part of a name, symbol or unit, such as planck, charge or mol, to filter the table. Every constant shows its value, unit and the name to use in calculations. Constants marked exact are fixed by definition, such as the speed of light and, since 2019, the Planck and Avogadro constants.
Calculating with constants
In the second field, write a calculation using the names from the last column. h * c / 500e-9 gives the energy of a photon with a wavelength of 500 nm (3.97 × 10⁻¹⁹ J). G * Mzon / AE^2 gives the Sun's gravitational pull at the Earth's distance. Scientific notation such as 500e-9 works, and so do sqrt, ^ and pi.
The table follows the Dutch Binas reference book used in schools, which is where some names such as AE and Mzon come from.
Frequently asked questions
Is the physical constants free?
Yes. The physical constants is completely free, with no account, sign-up or usage limit.
How accurate is the result?
The tool calculates with your browser's number precision. For important calculations, always double-check what you entered.
Does it work on my phone?
Yes. The tool works in any modern browser on a phone, tablet or computer.