Lamp brightness is expressed as MSCP (Mean Spherical Candlepower). MSCP is an industry-wide standard of measurement that effectively integrates and averages the brightness of a lamp in all axes.

To convert MSCP to lumens, multiply by 12.57 (4 pi).

MSCP of a lamp is derived by centering the lamp within an integrating sphere (see below) with an interior diameter of one foot (30,5 cm). The interior of the sphere has a bright-white, matte coating that disperses and reflects the light evenly.

A photocell in the base of the sphere converts the light energy to electrical current, and sends the current to specialized instrumentation for measurement.

A baffle mounted below the lamp shields the photocell from direct illumination by the lamp, ensuring measurement of a true average of the light produced by the lamp.