These tables, formulas and numbers do not intend to present the most accurate numbers
up to the least decimal digit (factors between 0.5 and 2.0 were usually ignored). If you look for exact figures,
this is the wrong place.
Instead they want to visualize the vast scales in which Physics is operating,
and also the tremendous scale gaps between them.
The smallest known unit with physical meaning is the 'Planck length' lPl ≈ 10-35m.
It is a theoretical value, which gives a link between quantum effects and gravitation. But most remarkably,
the next scale with a physical meaning (the wavelength of the heaviest elementary particles) is 1017 times larger.
(This ratio is, by the way, nearly the same as the Earth radius compared to the radius of a hydrogen atom!)
Current physics has no explanation of this vast gap.
Natural Unit Converter
Mass [MeV]
Mass [kg]
Length [m]
Time [s]
Planck units
Here you can enter one value and all correspondent units will be computed
Table of Universal Physical Scales
Thanks to Theo Langhammer (hans.langhammer@physik.uni-halle.de) for his help in correcting my errors.