Certain factors, such as the room's size, color scheme, and intended use, actively determine the number of lumens required for indoor lighting. Here's a rough guideline:
For a room used for detailed tasks, like a kitchen or a reading area, consider around 70-80 lumens per square foot.
For moderate, general activities like in a living room, 20-30 lumens per square foot is usually sufficient.
For low-light areas like bedrooms or dining rooms, 10-20 lumens per square foot is often adequate.
The mentioned lumens per square foot, or foot candles, are generally accepted values used in lighting design. The Illuminating Engineering Society (IES) provides a range of recommended light levels for different tasks and room types. Similarly, the National Electrical Manufacturers Association (NEMA) provides guidelines on light levels in industrial settings.
Keep in mind that individual preferences and room layouts can cause variations. Always consider the room's use and actively adjust your lighting to suit.