Lighting Calculator
Calculate lumens, fixtures, and LED wattage needed
Floor area of the room
Determines required footcandles
Number of Fixtures
—
fixtures
LED Watts
—
watts
Lumens Needed
—
lumens
Disclaimer: Results are estimates based on standard formulas. Not a substitute for professional advice from a licensed contractor, engineer, or architect. Verify all calculations before making purchasing or construction decisions.
How to Use This Calculator
Proper lighting design balances brightness, energy use, and comfort. Our calculator uses IES footcandle recommendations to size your fixture layout.
- Measure the room floor area in square feet
- Select the room type to set footcandle target
- Review total lumens, fixture count, and LED watts
- Space fixtures evenly for uniform illumination
Expert Insights
Smart analysis for your Electrical project
Footcandle Standards
IES recommends 20 fc for living areas, 40 fc for offices, 50 fc for kitchens, and 30 fc for garages. AI applies the correct target automatically.
LED Efficiency Gains
LEDs deliver roughly 100 lumens per watt versus 15 for incandescent. AI estimates LED wattage so you can size circuits and save energy.
Color Temperature Guidance
2700K-3000K for living areas, 3500K-4000K for kitchens, 5000K for garages. AI reminds you to match color temperature to room function.
Calculation Formula
Footcandles: Kitchen = 50, Office = 40, Garage = 30, Living = 20
Lumens = Room area x Footcandles
Number of Fixtures = ceil(Lumens / 800)
LED Watts = ceil(Lumens / 100)
Bulb Type Comparison
| Bulb Type | Lumens/Watt | Lifespan | 800 lm Equivalent | Color Quality |
|---|---|---|---|---|
| LED | 80-100 | 25,000-50,000 hrs | 9-10W | Excellent |
| CFL | 55-70 | 8,000-10,000 hrs | 13-15W | Good |
| Halogen | 15-20 | 2,000-4,000 hrs | 43W | Excellent |
| Incandescent | 10-15 | 1,000-2,000 hrs | 60W | Excellent |
Authority References
Our calculations are based on guidelines and standards from these authoritative sources:
- Illuminating Engineering Society (IES) — Lighting Handbook — Footcandle Recommendations. Learn more
- U.S. Department of Energy (DOE) — LED Lighting Energy Efficiency Guidelines. Learn more
- National Fire Protection Association (NFPA) — NFPA 70 — NEC Article 410 — Lighting Fixtures. Learn more
Frequently Asked Questions
How many lumens do I need per square foot?
Living rooms need 10-20 lumens per sq ft, offices 30-40, kitchens 50-70, and garages 30-50. Multiply the room area by the footcandle requirement for total lumens.
How many LED watts equal a 60W incandescent bulb?
A 60W incandescent bulb produces about 800 lumens, which an LED achieves with only 9-10 watts. LEDs use roughly 1/6 the wattage for the same light output.
How many light fixtures do I need for a 200 sq ft kitchen?
A kitchen needs about 50 footcandles, so 200 sq ft requires 10,000 lumens. At 800 lumens per fixture, you would need 13 fixtures (ceiling lights or recessed cans).