Fixtures Needed
12
Layout
4 × 3
Total Watts
120 W
Annual Cost
$16
12
4 × 3
120 W
$16
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Inputs
Result
Area = 15 x 12 = 180 sq ft. Lumens = 180 x 50 = 9,000. Fixtures = 9000 / 800 = 11.25, rounded up to 12. Grid: 4 x 3. Cost = (120W / 1000) x 3 x 365 x 0.12 = $15.77.
Inputs
Result
Area = 14 x 12 = 168 sq ft. Lumens = 168 x 15 = 2,520. Fixtures = 2520 / 800 = 3.15, rounded up to 4. Grid: 2 x 2. Cost = (40W / 1000) x 3 x 365 x 0.12 = $5.26.
It depends on room type: kitchen and office need 50 lm/sq ft, bathroom 40, garage 30, living room 20, and bedroom 15. Task areas like countertops may need more supplemental lighting.
| Room Type | Lumens/sq ft | Example: 200 sq ft Room | Typical Fixture Count |
|---|---|---|---|
| Kitchen | 50 | 10,000 lm | 12–14 |
| Bathroom | 40 | 8,000 lm | 8–10 |
| Office/Workshop | 50 | 10,000 lm | 12–14 |
| Living Room | 20 | 4,000 lm | 5–6 |
| Bedroom | 15 | 3,000 lm | 4 |
| Garage | 30 | 6,000 lm | 6–8 |
A general rule is spacing recessed lights at half the ceiling height apart. For an 8-foot ceiling, space lights about 4 feet apart. Edge clearance (distance from wall) should be half the spacing distance.
For a kitchen (50 lm/sq ft): 180 sq ft x 50 = 9,000 lumens. With 800-lumen fixtures, you need 12 fixtures. For a living room (20 lm/sq ft): 180 x 20 = 3,600 lumens, or 5 fixtures.
No. LEDs produce far more lumens per watt. A 10W LED produces about 800 lumens, equivalent to a 60W incandescent. Always compare fixtures by lumens (brightness), not wattage.
| Lumens (Brightness) | LED Watts | Incandescent Watts | Annual Cost (3 hr/day) |
|---|---|---|---|
| 450 lm | 4–5W | 40W | $2.19 vs $17.52 |
| 800 lm | 8–10W | 60W | $3.94 vs $26.28 |
| 1100 lm | 13–15W | 75W | $5.69 vs $32.85 |
| 1600 lm | 16–20W | 100W | $7.88 vs $43.80 |
| 2600 lm | 25–28W | 150W | $10.95 vs $65.70 |
A grid pattern with equal row and column spacing provides the most even illumination. Place the first row at half the spacing distance from the wall. Aim for a symmetrical grid that covers the room evenly.
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Last Updated: Oct 19, 2026
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