The speed of light in a vacuum, denoted by the symbol "c," is approximately 299,792,458 meters per second.
A Planck length, denoted by the symbol "ℓP," is a unit of length in the system of natural units derived from fundamental physical constants. It is approximately equal to 1.616255(18) × 10^−35 meters.
To calculate the speed of light in Planck lengths, we divide the speed of light by the Planck length:
c/ℓP ≈ 299,792,458 m/s / (1.616255 × 10^−35 m) ≈ 1.85487 × 10^43 Planck lengths per second.
Therefore, the speed of light is roughly 1.85487 × 10^43 Planck lengths per second.