How Many Lumens Do You Need Per Square Foot?

Whether cooking a meal, reading a book, or working out in the garage, we all need proper lighting in our homes and workplaces. The wrong lighting can make the room too dark when it should be brighter, or too bright when the light should be softer. Low light can even make performing tasks around a home or business unsafe. But with the right amount of light, you can get the job done safely!

Planning the right lighting means knowing how many lumens you need to brighten up the space. Lumen is a unit of luminous flux and measures the amount of visible light you get from a bulb. To figure out the recommended lumens for the space, consider the following:

The first step in figuring out the lumens needed is to measure the size of the room being lit. A larger room needs more lumens than a smaller one. To calculate the square footage, begin by measuring the length of the room in feet. Next, measure the width of the room. To get the room square footage, multiply the length by the width.

Length of the room (in feet) x Width of the room (in feet) = Square footage (sq. ft.)

For example, a room that measures 20-ft in length x 10-ft in width = 200 sq. ft.

Next, consider the amount of foot candles the room needs. A foot candle measures how bright a light source appears when standing one foot away. One foot candle equals one lumen per square foot.

The number of foot candles required changes depending on the purpose of the room. Rooms designed for tasks, like kitchen stove and sink areas or garages, need more foot candles than a hallway or bedroom. The requirements can also differ depending on the type of space. More work- or task-oriented locations, such as warehouses, schools, or hospitals, may require a higher amount of foot candles than a similar room in a home.

The following are for residential locations:

• Bedroom: 10-20 foot candles
• Dining room: 30-40 foot candles
• Kitchen (general): 30-40 foot candles
• Kitchen (stove and sink areas): 70-80 foot candles
• Hallway: 5-10 foot candles
• Bathroom: 70-80 foot candles

After finding the square footage of the room and figuring out the required foot candles, you can determine how many lumens the room needs. To do this, multiply the square footage of the room by the foot candle requirement.

For example, finding the number of lumens needed for a 200 sq.ft. room that needs 10-20 foot candles:

200 sq.ft. x 10 foot candles = 2,000 lumens

200 sq. ft. x 20 foot candles = 4,000 lumens

Keep in mind that this number may vary depending on certain room factors. Rooms with dark walls or high ceilings may require more lumens to achieve the perfect brightness. This equation gives you a general number of lumens per sq ft to aim towards.