Recessed Lighting Calculator

With the calculator’s current example settings, a 12 × 12 ft room needs 6 recessed lights in a 3 × 2 grid. The example uses an 8 ft ceiling, a floor-level calculation plane, a 13.94 fc target (150 lux), and 850-lumen, 90° fixtures.

With utilization 0.55, light loss 0.8, and spacing ratio 1.5, the estimated average is 15.58 fc (168 lux). The grid has 6 ft spacing across the width and 4 ft along the length, with 3 ft and 2 ft wall offsets respectively. Different brightness targets, fixtures, or calculation heights can change the result; six lights is not a rule for every 12 × 12 ft room. See the light-count guide and compare lighting layouts.

Using the kitchen estimates above, an 8 × 10 ft kitchen returns 4 recessed lights; 10 × 10 ft and 10 × 12 ft return 6; 12 × 12 ft returns 8; and 12 × 15 ft returns 9. These examples use an 8 ft ceiling, about a 3 ft workplane, 850-lumen fixtures, and an 18.58 fc (200 lux) target light level.

For a different kitchen, select Kitchen · general, enter the room dimensions and complete-fixture lumens, and review the calculated can-light layout. This calculator estimates general lighting for a rectangular room; it does not account for cabinets, islands, shadows, or dedicated countertop task lighting. Selecting Kitchen changes the target, not Workplane Height, so apply the suggested height separately or enter the actual surface height in the calculator.

There is no fixed number of recessed lights per square foot that fits every room. This calculator starts with room area × target foot-candles ÷ (fixture lumens × 0.55 utilization × 0.8 light loss), then rounds up. Auto may increase that starting count so a complete grid also meets the calculator’s spacing limit.

Use the calculation method to understand the estimate, then enter the actual room use and complete-fixture output instead of relying on a universal lights-per-square-foot ratio.

Yes. Enter the total lumens and beam angle from the complete LED fixture’s packaging or specification sheet; wattage is optional and describes power use, not brightness. Choose a listed, source-checked model—including the listed HALO configurations—or enter custom specifications.

A housing model or the word LED alone does not establish light output, and this tool has no manufacturer certification. Use the complete-fixture specifications to calculate the recessed lighting layout.

There is no single fixture count. Circuit voltage and amperage, each fixture or driver’s wattage, other loads, dimmer and driver ratings, startup current, protection, and local requirements all matter.

This calculator only totals fixture watts; it does not assess breaker or circuit capacity. Review what the estimate covers and have an electrician check the actual circuit before installation.