The formula to calculate lumens ($L$) is:

$$L = \frac{E_{av} \times L_{room} \times W_{room}}{0.32}$$

Where:

• $L$ is the lumens (lm).
• $E_{av}$ is the average illuminance in lux (lx).
• $L_{room}$ is the length of the room in meters.
• $W_{room}$ is the width of the room in meters.