Physical constants can take many dimensional forms: the speed of light signifies a maximum speed for any object and its dimension is length divided by time; while the fine-structure constant α, which characterizes the strength of the electromagnetic interaction, is dimensionless.

Are all constants dimensionless?

All constants are dimensionless.

Do constants have dimensional formula?

So, dimensional constants are those quantities whose values are constant, and they possess dimensions. For example, Gravitational constant, Boltzmann constant, Planck's constant, etc.