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Mastering Light & Illuminance
Lighting isn't just about finding a switch in the dark; it affects our mood, productivity, and eye health. Illuminance (measured in Lux) tells us exactly how much light is landing on your desk or dinner table. Our calculator helps you design the perfect lighting standard for any room.
Architectural Lighting Tools
Lighting Calculator
Input your Room Area and Bulb Lumens to see if your setup is "Cozy", "Productive", or "Too Dark".
Lux to Foot-candles
Working with US Blueprints? Convert standard Lux specs to Foot-candles (fc) instantly.
Eye Health
Prevent eye strain. Ensure your home office hits the recommended 500 Lux standard.
How to Calculate Lighting?
The Simple Formula
Illuminance ($E$) is basically the density of light. It is calculated by dividing total Luminous Flux ($\Phi$) by the Area ($A$).
Example: A 20 $m^2$ living room with two 800-lumen bulbs (1600 total lumens):
1600 / 20 = 80 Lux. (This is quite dim/cozy).
Common Standards
Frequently Asked Questions
What is the difference between Lux and Lumens?
Lumens measure the total light emitted by a bulb. Lux measures how much of that light actually hits a specific surface (intensity). Think of Lumens as water flowing from a hose, and Lux as how wet the grass gets.
How many Lux do I need for a home office?
For standard computer work and reading, aim for 500 Lux. Lower levels (300 Lux) are okay for paperless work, but detailed drafting may require 750-1000 Lux.
How do I calculate Lux from Lumens?
The simple formula is: Lux = Total Lumens ÷ Area (m²). For example, a 1000 lumen bulb in a 10m² room gives 100 Lux (assuming perfect reflection/distribution).
What is a Foot-candle?
A Foot-candle (fc) is the US customary unit for illuminance. It equals one lumen per square foot. 1 Foot-candle ≈ 10.76 Lux.
Is 100 Lux bright enough?
No, 100 Lux is considered dim. It's suitable for hallways, elevators, or relaxing in a living room, but too dark for reading or cooking (which need 300+ Lux).
What is Daylight Lux?
Direct sunlight can reach 100,000 Lux. An overcast day is about 1,000 Lux. A full moon is barely 0.1 Lux.
Why does my room look dark even with high Lumens?
Dark walls absorb light! The Lux calculated by our tool assumes the light reaches reflection. If you have black walls, you might need 2x or 3x more lumens to achieve the same perceived brightness.
What is a Phot?
A Phot (ph) is a CGS unit equal to 10,000 Lux. It's extremely bright and rarely used outside of scientific contexts involving lasers or sun equivalents.
How many lumens is a 60W bulb?
A standard incandescent 60W bulb produces about 800 Lumens. An LED equivalent consumes only ~9 Watts for the same output.
What is the recommended Lux for a kitchen?
Kitchens need bright light for safety (chopping/cooking). Aim for 300-500 Lux general lighting, with task lighting under cabinets reaching 750 Lux.