💡 Interactive Lumens & Lighting Calculator
Enter your room dimensions and select its primary functional purpose.
How room lighting is calculated
Architects and lighting designers calculate artificial illumination using foot-candles or lux:
- 1 Foot-Candle (fc) = 1 Lumen per square foot of area.
- 1 Lux = 1 Lumen per square metre (1 fc ≈ 10.76 Lux).
- Formula: Total Lumens Required = Room Area (sq ft) × Target Foot-Candles.
Standard Foot-Candle Requirements by Room
| Room Function | Target Foot-Candles | Recommended Colour Temp (Kelvin) | Best Fixtures |
|---|---|---|---|
| Living Room | 15 to 20 fc | 2700K " 3000K (Warm White) | Dimmable downlights, floor lamps, sconces |
| Kitchen Counters | 50 to 60 fc | 3500K " 4000K (Bright Neutral) | Under-cabinet LED strips, focused pendants |
| Bedroom | 15 to 20 fc | 2700K (Soft Candle-warm) | Central diffuse fixture, bedside reading lamps |
| Home Office | 50 fc | 4000K (Crisp Cool White) | Anti-glare ceiling panels, directional task lamp |
| Bathroom Vanity | 50 to 60 fc | 3000K " 4000K (High CRI 90+) | Vertical sconces flanking mirror (no top shadow) |
The Three Layers of Lighting Architecture
A single overhead light bulb creates harsh shadows and a flat, uninviting atmosphere. Professional decorators always employ three distinct layers:
- Ambient (General) Lighting: Provides safe overall visibility. Achieved via recessed ceiling pots, flush mounts, or central chandeliers.
- Task Lighting: High-intensity directional light positioned directly over working surfaces: kitchen chopping boards, reading chairs, and bathroom mirrors.
- Accent Lighting: Decorative highlight illumination (roughly 3x brighter than surrounding ambient) used to draw attention to artwork, architectural alcoves, and shelving plants.
Frequently asked questions
What is the difference between Watts and Lumens?
Watts measure electrical energy consumption, while Lumens measure actual brightness (visible light output). Modern LED bulbs produce about 80 to 100 lumens per watt, compared to old incandescent bulbs that yielded only 14 lumens per watt.
What bulb colour temperature is best for bedrooms?
Warm white (2700K) is optimal for bedrooms. Higher Kelvin ratings (5000K blue-white) inhibit melatonin production and disrupt sleep cycles.
Disclaimer: This calculator provides architectural planning estimates. Dimmable circuits, ceiling heights above 9 feet, and dark wall paint colors will require 15-20% additional lumens.