Estimating LED Lumens for Your Space

These days, LED lights are routinely used throughout residential and commercial building projects. Outdoor roads, tunnels, building facades, indoor offices and shop floors are entirely lit using LED lighting. LEDs use significantly less energy than fluorescent or incandescent lights and the price has come down dramatically. So what if you’re getting ready to switch to LED lighting in your home or office? How many LED lights, or LED lumens, will you need to light a room?

Identifying key terms

Lumens A measurement of light emitted by a source. It can be LED, fluorescent, halogen or incandescent. Also known as “brightness” or “light output.” Reference point: A standard 100-watt incandescent light bulb produces about 1,500 – 1,700 lumens.

Watts A measure of how much electricity (or energy) a bulb consumes to reach its claimed brightness. Each type of light source, LED, fluorescent, halogen, or incandescent has a different lumen-per-watt ratio.  Below we’re going to use lumens as a measurement to make sure we have enough light for a space.

A wattage equivalence chart; note that lumen-per-watt ratios can vary

Roberts Electric lumens to watt conversion chart

Efficacy The number of lumens a bulb produces for each watt it consumes. The higher the number, the more efficient the bulb. Lighting products that have earned the ENERGY STAR label are high efficacy–they deliver the same features while using less energy.

The Breakdown: How much light is enough light? 

Determine room square footage Multiply the length x the width of the room to get the room square footage. If the room is 10’ x 10’, the room square footage will be 100 square feet.

Determine the foot candles by room type or room purpose A foot-candle is how bright a light is one foot away from its source. Lighting requirements/needs vary depending on the type of room being lit. A bathroom or kitchen will require more foot candles than a living room or bedroom.

Roberts Electric watts to lumens conversions

Determine the needed lumens
A lumen is a unit measurement of light. To determine the needed lumens, you will need to multiply your room’s square footage by your room’s 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.

A quick summary

For the average space of 250 square feet, you’ll need roughly 5,000 lumens as your primary light source (20 lumens x 250 square feet). In your dining room, you’ll want about 30 lumens per square foot on your dining table (you want to see your food, but not examine it), so if your table is 6’ x 3’, that’s 540 lumens.

roberts electric measuring lumens for your home or office

Keep in mind that these numbers are for typical conditions. If your walls and furniture are dark, or if you’re using fixtures with shades, you’ll need roughly an additional 10 lumens/square foot. We based our calculations on 8-foot ceilings. Personal preference will play the largest part in your decision. If you like the room to be especially bright, you may want to add an additional 10 to 20% to our numbers.

The best approach?

Aim high and install dimmers to reach the desired levels.

Contact Info


Roberts Electric Co., Inc.
2408 Webster Street
Oakland, CA 94612


Tel: (510) 834-6161
Fax: (510) 834-4929
info@robertselectric.com

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ROBERTS ELECTRIC IS PROUD TO BE NAMED ONE OF THE TOP 25 LARGEST ELECTRICAL CONTRACTORS BY THE SAN FRANCISCO BUSINESS AGAIN FOR 2019. WE’VE MADE THE LIST 9 TIMES IN THE LAST 11 YEARS.

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ROBERTS ELECTRIC HAS BEEN NAMED ONE OF THE TOP 25 LARGEST ELECTRICAL CONTRACTORS BY THE SAN FRANCISCO BUSINESS 9 TIMES IN THE LAST 11 YEARS. WE WERE NAMED TO THE LIST AGAIN FOR 2019. WE ARE ALSO PROUD TO BE A DIAMOND-CERTIFIED COMPANY FOR 18 STRAIGHT YEARS

Roberts Electric is proud to be entrusted with serving former clients of All Electric and Broadmoor Electric. We are committed to continuing their rich tradition of customer service.

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