The intensity is defined as power per unit area, and power is defined as energy per unit time. Thus: I=PA=EΔt1A.

Lux, unit of illumination (see luminous intensity) in the International System of Units (SI). One lux (Latin for “light”) is the amount of illumination provided when one lumen is evenly distributed over an area of one square metre.

Light can be measured subjectively, based on the brightness seen by the human eye. Units include candles, lumens, footcandles and lux. A source of light has a luminosity of one candle if its output appears to match that of a “standard candle”.

The SI unit of luminous intensity is the candela (cd), an SI base unit….

Lighting Calculation – Summary Calculate the amount of lumens you need. Multiply the area in square meters by the lux, or the area in square feet by the footcandles. work out how many bulbs you need. Divide the number of lumens by the number of lumens delivered by each bulb.

If you’re trying to figure out LED lighting for your kitchen counter, the illuminated area will be calculated as the length of the counter multiplied by its width. You can use illumination units of lux or foot candles. If you want to recalculate between these units, remember that one foot-candle equals 10.764 lux.

For the average living room of 250 square feet, you’ll need 5,000 lumens as your primary light source (20 lumens x 250 square feet), equivalent to about five 100 watt incandescent light bulbs, five 23 watt CFLs, or eight 10 watt LED light bulbs.

To determine the needed lumens, you will need to multiply your room square footage by your room foot-candle requirement. For example, a 100 square foot living room, which needs 10-20 foot-candles, will need 1,000-2,000 lumens. A 100 square foot dining room, which needs 30-40 foot-candles, will need 3,000-4,000 lumens.

Determine the space area Use the length of the room to multiply the width of the room to get the size of the room. For example, a room 10 feet wide and 10 feet long, then his area is 100 square feet. Footlights indicate the brightness of a light source measured from a distance of one foot.

LED equivalents to traditional incandescent light bulbs