What Is Considered Enough Light?
It’s a common question—and not always an easy one to answer. Figuring out how much LED lighting you need to effectively brighten a space can be a bit complex.
Whether you’re planning for commercial architectural lighting or residential applications, understanding how to calculate the right number of LED lumens is essential. Here’s a breakdown of what you need to know.
Key Lighting Terms
Lumens
Lumens measure the total amount of visible light emitted by a source—be it LED, fluorescent, halogen, or incandescent. This measurement reflects the brightness or light output. As a point of reference, a standard 100-watt incandescent bulb produces about 1,500 to 1,700 lumens.
Watts
Watts indicate how much energy a light source consumes, not how bright it is. Since different light technologies produce varying amounts of light per watt, we’ll focus on lumens to assess lighting needs more accurately.
Wattage Equivalence
Because many people still think in terms of watts, you’ll often see LED bulbs labeled with “watt equivalents.” For instance, if a 10-watt LED produces the same 1,500 lumens as a 100-watt incandescent, it might be marketed as a “100-watt equivalent” bulb. However, lumen-per-watt performance can vary slightly between different LED products and fixture types, like suspended linear lighting or recessed options.
Efficacy
Efficacy refers to the number of lumens a bulb produces per watt it uses. Higher efficacy means better energy efficiency. ENERGY STAR-certified lighting products typically offer high efficacy, delivering strong performance with lower energy use.
How to Calculate How Much Light You Need
1. Measure the Room’s Square Footage
Multiply the room’s length by its width. For example, a 10′ x 10′ room equals 100 square feet.
2. Identify the Recommended Foot-Candles for the Room Type
Foot-candles measure how much light falls on a surface one foot away from the source. Different rooms require different levels of brightness. Kitchens and bathrooms need more foot-candles than bedrooms or living rooms.
3. Calculate the Required Lumens
To find out how many lumens you need, multiply your room’s square footage by the required foot-candles for that type of space.
For a 100 sq. ft. living room needing 10–20 foot-candles: you’ll need 1,000–2,000 lumens.
For a 100 sq. ft. dining room needing 30–40 foot-candles: you’ll need 3,000–4,000 lumens.
Quick Reference Example
A typical 250 sq. ft. room would require around 5,000 lumens for general lighting (based on 20 lumens per square foot). For more focused lighting—like over a dining table—you might aim for about 30 lumens per square foot. A 6′ x 3′ table would therefore need around 540 lumens.
Additional Tips
Dark interiors (walls, furniture, finishes) absorb more light, so you may want to add about 10 lumens per square foot.
Ceiling height matters—these examples assume 8-foot ceilings.
Personal preference is key. If you prefer brighter spaces, consider increasing your lumen count by 10–20%.
Use dimmers where possible. This allows flexibility to adjust brightness depending on time of day or activity.
