lux - to - vMag

The Illuminance to Apparent Magnitude calculator computes the apparent magnitude based on the illuminance.

INSTRUCTIONS: Choose units and enter the following:

• (E_v) Illuminance of the Star

Apparent Magnitude (Mv): The calculator returns the magnitude as a real number.

The Math/ Science

This equation computes the apparent magnitude (`M_v`) from the input illuminance (`E_v`) input as units of lux (lx).  The formula for Apparent Magnitude from Illuminance is:

Mv = -14.18 - 2.5 * log(Ev)

where:

• Mv = Apparent Magnitude of the celestial body
• Ev = Illuminance in lux

Illuminance is the measure of the amount of light (luminous flux) incident on a surface.

Apparent Magnitude is a measure of a celestial body's brightness as seen by an observer on Earth.  The Apparent Magnitude is adjusted to the value it would be in the absence of atmosphere.