About Recessed Light Calculator

Recessed Light Calculator is a free planning tool for recessed and downlight installs — fixture count, center-to-center spacing, wall offset, and brightness in foot-candles and lux, all from a room's dimensions and ceiling height.

It's built for anyone planning a lighting layout before drywall goes up or before an electrician quotes a retrofit: homeowners sketching out a renovation, electricians double-checking a quick estimate on-site, and contractors and interior designers who want a fast first pass before a full photometric design.

Every calculator on this site runs the IESNA lumen method — the same first-pass approach professional lighting designers use before running a complete photometric design: total lumens needed comes from floor area multiplied by a target foot-candle level, and that divides by a fixture's rated output to give a fixture count, which is then checked against a complete, evenly spaced grid.

These are planning estimates, not a substitute for a stamped photometric design or a review against local electrical code. Head back to the recessed light calculator to start planning a layout.