How to Calculate Recessed Lighting Spacing

Consult the recessed lighting units you wish to install to find the “spacing criterion.” You may find the lighting package labeled with a number and then the initials “SC,” or the spacing criterion may also be called “Space to Mounting Ratio.” This is the ratio for the most distance you want between two recessed lighting units.

Measure the distance from the ceiling down to the surface you wish to light -- the floor or a countertop, for example. If you wish to illuminate the floor and you have 8-foot ceilings, use 8 feet for calculating. If you wish to illuminate a countertop 3 feet from the floor and you have 8-foot ceilings, subtract 3 feet from 8 feet to make 5 feet for calculating.

Multiply the spacing criterion number by the number of feet. For example, if the spacing criterion number was .5, multiply .5 * 8 = 4 (the spacing between recessed lighting units to illuminate the floor). Multiply .5 * 5 = 2.5 (the spacing between recessed lighting units to illuminate the counter).