Lighting Calculator
Size lighting layouts using foot-candle recommendations, fixture output, and daylight contribution to achieve balanced illumination in any room.
Target foot-candles: 20 fc
Required Lumens
5,355 lumens
Daylight factor: 15%
Fixtures Needed
5 fixtures
Fixture output: 1100 lm each
Power Requirement
60 watts total
Fixture count is typical. Space fixtures evenly and use dimmers to adjust light levels for different tasks.
How to Use This Calculator
Measure the room
Enter room length, width, and ceiling height to calculate square footage and choose an appropriate foot-candle target.
Choose fixture specs
Select the lumen output and wattage of the fixture you plan to install—recessed, track, or ceiling lights.
Adjust for daylight
If the room receives natural light, reduce artificial lighting need by entering a daylight contribution percentage.
Formula
Required Lumens = (Area × Foot-Candles × (1 − Daylight %)) ÷ Light Loss Factor
Fixtures = ceil(Required Lumens ÷ Fixture Lumens)
Example: 18 × 14 ft living room → 252 sq ft. Target 20 fc → 5,040 lumens. Daylight 15% → 4,284 lumens. ÷ 0.8 LLF → ~5,355 lumens. Using 1,100 lm fixtures → 5 fixtures.
About the Lighting Calculator
Proper lighting mixes ambient, task, and accent layers. This calculator gives a baseline for ambient lighting so designers and homeowners can plan layouts that meet industry illuminance levels.
When to Use This Calculator
- Remodel planning: Determine how many recessed cans or ceiling fixtures to install.
- Lighting upgrades: Compare fixture layouts when switching to LEDs.
- Commercial tenant fit-outs: Verify lighting levels meet code or company standards.
- Home theaters & studios: Balance ambient light before layering task and accent lighting.
Why Use Our Calculator?
- ✅ Code-aligned: Uses common foot-candle targets from IES guidelines.
- ✅ Daylight aware: Reduces artificial light needs when natural light is available.
- ✅ Fixture flexible: Works with recessed, pendant, or track lighting by lumen output.
- ✅ Mobile ready: Calculate on-site during consultations.
Common Applications
Electricians: Plan circuits and load requirements for new lighting layouts.
Interior designers: Validate ambiance levels for different room types.
DIY homeowners: Purchase the right number of fixtures before installation.
Tips for Best Results
- Layer lighting: add task lights over counters and accent lights for mood.
- Use dimmers to fine-tune light levels throughout the day.
- Balance fixture spacing to avoid uneven light distribution.
- Account for ceiling height—taller ceilings may need higher output fixtures or additional layers.
Frequently Asked Questions
What are foot-candles?
A foot-candle measures light intensity on a surface. Different rooms require different levels for safety and comfort.
How do I factor task lighting?
Use this calculator for ambient lighting, then add task lights (under-cabinet, desk lamps) where focused light is needed.
Do LED color temperatures affect brightness?
Color temperature doesn’t change lumen output but influences perceived brightness. 2700–3000K feels warm; 4000K feels crisp.
How accurate are daylight adjustments?
Daylight contribution is an estimate. Use lighting controls or sensors for precise daylight harvesting.