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.
Three calculations to copy
| Question | Type this | Result |
|---|---|---|
| Rest energy of the electron | me * c^2 |
8.187 × 10⁻¹⁴ J |
| Molar volume of a gas at 0 °C and 1 atm | R * 273.15 / 101325 |
0.02241 m³ (22.41 L) |
| Pull of the Sun at Earth's distance | G * Mzon / AE^2 |
5.93 × 10⁻³ m/s² |
Reading the table
Each row shows the quantity, its symbol, the value, the unit and the name to type in the calculation field. The search filter matches any of these, so kelvin finds the Boltzmann constant and mol the Avogadro constant. For the physics of oscillations, see simple harmonic motion, and for powers of ten, the exponent calculator.
Scientific notation
Type very large and small values with an e: 6.02e23 or 500e-9. Results are shown as a number times a power of ten, with a line giving more digits.
Frequently asked questions
Which constants are exact?
Since the 2019 redefinition of the SI units, the speed of light, the Planck constant, the elementary charge, the Boltzmann constant and the Avogadro constant are exact by definition. Those are marked *exact* in the table.
How do I convert a photon's energy to electron volts?
Divide the energy in joules by the elementary charge: `h * c / 500e-9 / qe` gives about 2.48 eV for a wavelength of 500 nm.
What are Binas and the names such as AE and Mzon?
Binas is the Dutch science reference book used in schools, and the short names follow it. AE is the astronomical unit and Mzon the mass of the Sun.
Which units do the values use?
SI units: metres, kilograms, seconds, joules and so on. The unit is shown next to every constant, and results come out in the matching SI unit.