Planck length: a natural scale of distance

planckLength is the length constructed from the gravitational constant, reduced Planck constant, and speed of light. It is extraordinarily small and marks a natural scale where quantum-gravity effects are expected to matter.

Context

It is a theoretical unit, not a measured minimum length. It accompanies planckTime and planckMass in Planck-unit systems.

Caveats

Do not interpret the constant as proof that space is physically discrete. Convert to SI metres carefully and retain scientific notation using format; compare ordinary propagation scales with speedOfLight.

Use Planck Length in a calculation

Enter planckLength on a calculator line to see its built-in value, or place the name inside a longer expression. Keep any displayed unit attached when converting or combining physical quantities, and check that every other value uses a compatible dimension.

The example above is editable, so you can replace surrounding values and test the constant in your own formula. Browse all constants to compare related values and notation.