To find the right bulb brightness, start from the room's function and area, then choose the target light level measured in lux, and calculate the total lumens needed. The right intensity gives comfortable vision without glare or dimness.
Quick answer: Lux = lumens ÷ area (m²). Pick the recommended lux for the room's function, then multiply by the area to find the total lumens you need.
Lumens vs. lux
- Lumen: The total light output from the bulb.
- Lux: The light intensity reaching a surface (lumens per square meter).
So the same bulb gives higher lux in a small room and lower lux in a large one.
Recommended lux levels per room
- Bedrooms: about 100–200 lux (soft lighting).
- Living rooms: about 150–300 lux.
- Kitchen (general): about 300 lux, prep surfaces 500 lux.
- Office/reading: about 400–500 lux.
- Bathroom: about 200–300 lux, higher at the mirror.
- Hallways and entrances: about 100–150 lux.
How to calculate required lumens (example)
A 20 m² living room that needs 200 lux:
Lumens = 200 lux × 20 m² = about 4000 lumens, spread across several light sources.
Factors that affect brightness
- Ceiling height: The higher the ceiling, the less lux reaches the floor.
- Wall and furniture color: Light colors reflect light and increase brightness.
- Beam angle and distribution: Good distribution prevents dark spots.
- Color temperature: Doesn't change lux but changes how bright it feels.
Signs the brightness is wrong
- Too dim: Eye strain and difficulty seeing.
- Too bright: Glare and visual fatigue.
- Solution: Use layered lighting (ambient + task + accent).
Frequently asked questions
How do I know the lighting is enough?
Compare the actual lux to the recommended level for the room; you can measure it with a lux meter app.
One strong bulb or several bulbs?
Several distributed sources are better—they give even light without harsh shadows.
Is the same brightness right for all rooms?
No, it varies by function; kitchens and offices need more than bedrooms.
Conclusion
The right brightness starts with the target lux for the room's function, then calculating lumens by area, while accounting for ceiling height, colors, and distribution. That gives comfortable, balanced light everywhere.
Shop bulbs and fixtures in various brightness levels at Tirtk Lighting & Electrical
Related: Shop downlights and lighting at Tirtk.