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Lighting Layout Calculator

Plan fixture count, spacing, and energy cost for any room

Fixtures Needed

12

Layout

4 × 3

Total Watts

120 W

Annual Cost

$16

Units
Fixtures Needed

12

Layout

4 × 3

Total Watts

120 W

Annual Cost

$16

Lumens Breakdown

Room Area180.0 sq ft
Required Intensity50 lm/sq ft
Total Lumens Needed9,000 lm
Actual Lumens9,600 lm

Spacing Layout

Row Spacing (ft)3.0 ft
Col Spacing (ft)3.0 ft
Edge Clearance (ft)1.5 ft
Row Spacing3.0 ft
Column Spacing3.0 ft
Wall Clearance1.5 ft

Energy Cost

Total Wattage120 W
Usage3 hrs/day
Rate$0.12/kWh
Annual Cost$15.77
Monthly Cost$1.31

Example Calculations

1Kitchen Lighting (15 x 12 ft)

Inputs

Room Length15 ft
Room Width12 ft
Room TypeKitchen (50 lm/sq ft)
Fixture Lumens800 lm
Fixture Wattage10 W

Result

Fixtures Needed12
Room Area180 sq ft
Total Lumens9,000 lm
Grid Layout4 rows × 3 cols
Annual Cost$15.77

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.

2Bedroom Lighting (14 x 12 ft)

Inputs

Room Length14 ft
Room Width12 ft
Room TypeBedroom (15 lm/sq ft)
Fixture Lumens800 lm
Fixture Wattage10 W

Result

Fixtures Needed4
Room Area168 sq ft
Total Lumens2,520 lm
Grid Layout2 rows × 2 cols
Annual Cost$5.26

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.

Frequently Asked Questions

Q

How many lumens per square foot do I need?

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.

  • Task lighting (reading, cooking): Add 50–100% more lumens locally
  • Dimmer switches let you adjust brightness for different activities
  • Light wall color matters: Dark walls absorb 30–50% more light
  • Ceiling height above 9 ft: Add 10–20% more lumens per extra foot
  • Use the IES (Illuminating Engineering Society) standards for commercial spaces
Room TypeLumens/sq ftExample: 200 sq ft RoomTypical Fixture Count
Kitchen5010,000 lm12–14
Bathroom408,000 lm8–10
Office/Workshop5010,000 lm12–14
Living Room204,000 lm5–6
Bedroom153,000 lm4
Garage306,000 lm6–8
Q

How far apart should recessed lights be?

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.

  • Rule of thumb: Spacing = Ceiling Height ÷ 2
  • 8 ft ceiling: 4 ft spacing, 2 ft from walls
  • 9 ft ceiling: 4.5 ft spacing, 2.25 ft from walls
  • 10 ft ceiling: 5 ft spacing, 2.5 ft from walls
  • Overlap light cones by 50% for even coverage with no dark spots
Q

How many recessed lights do I need for a 12x15 room?

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.

  • Kitchen: 180 sq ft × 50 lm = 9,000 lm ÷ 800 lm/fixture = 12 fixtures
  • Living room: 180 sq ft × 20 lm = 3,600 lm ÷ 800 lm/fixture = 5 fixtures
  • Bedroom: 180 sq ft × 15 lm = 2,700 lm ÷ 800 lm/fixture = 4 fixtures
  • Grid layout for 12 fixtures: 4 rows × 3 columns (3.75 ft × 4 ft spacing)
  • Consider supplemental under-cabinet or pendant lights for task areas
Q

Do LED watts equal the same lumens as incandescent?

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.

  • LEDs produce ~80–100 lumens per watt vs incandescent at ~15 lm/W
  • LED lifespan: 25,000–50,000 hours vs incandescent 1,000 hours
  • LED color temp: 2700K (warm) to 5000K (daylight) – choose by room
  • CRI (Color Rendering Index): Pick 90+ CRI for kitchens and bathrooms
  • LEDs save 75–80% on energy vs incandescent at same brightness
Lumens (Brightness)LED WattsIncandescent WattsAnnual Cost (3 hr/day)
450 lm4–5W40W$2.19 vs $17.52
800 lm8–10W60W$3.94 vs $26.28
1100 lm13–15W75W$5.69 vs $32.85
1600 lm16–20W100W$7.88 vs $43.80
2600 lm25–28W150W$10.95 vs $65.70
Q

What is the best layout for recessed lighting?

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.

  • Grid pattern: Equal rows × columns for uniform coverage
  • First fixture: Half the spacing distance from each wall
  • Avoid placing lights directly over where people sit or stand
  • Kitchen: Add fixtures directly above countertops and sink
  • Use 4" or 6" cans – 6" is standard for general lighting, 4" for accents

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Last Updated: Mar 9, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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