Foot Candle Lighting Levels

Full Sun

• The lighting level for outdoors depends on many factors, including latitude, time of year and time of day. In general, though, the number of foot-candles provided by the sun in an average outdoor setting is about 8,000 to 12,000. This can be affected by nearby plants, buildings and reflective surfaces such as water and large white objects.

Indoor Direct Light

• Indoor direct lighting is lighting that is immediately in front of a window that faces south. This is the brightest natural light that comes into a home in most cases. It will also bring in the most heat from the sunlight. The general light level for this type of situation is about 1,500 foot-candles, which is quite bright. Many light-loving houseplants do well with direct lighting. Very bright artificial lights can re-create this level.

Strong Light

• Very strong light starts at about 5 feet away from a south-facing window. This light measures at about 300 foot-candles. A window that faces either west or east has this light level directly in front of the window, and a single 40-watt fluorescent tube gives off light in this range at a distance of about 6 inches. For growing indoor plants, a single or double fluorescent light can provide ideal lighting conditions when suspended directly above and close to the plants.

Bright Light

• Bright light, the average you might expect to find in a well-lit office, is about half the brightness of strong light, or 100 to 150 foot-candles. This is the light level that most people are comfortable with when working and is usually provide by the typical lighting in an office. Bright light levels exist as much as 10 feet away from windows with southern exposure, 4 feet from windows facing east or west, and immediately in front of any north-facing windows.

Normal Light

• Normal light levels are light levels that are much less than bright lighting levels. These levels are adequate for most purposes, though a room with houseplants may require more light. A normal lighting level is about 30 to 50 foot-candles. The available light 20 feet from a south window, 10 feet from an east or west window and 3 feet from a north window all fall into this category. Lamps may be added to increase the light in specific areas, if desired.