Understanding LED Wattage and Lumens
Published
When comparing LED strips, you will see two key specifications: watts and lumens. Many people confuse the two or assume that higher wattage always means brighter light. This guide explains what each measurement means, how they relate to each other, and how to use them to plan your project correctly.
Watts: Power Consumption
Watts (W) measure how much electrical power a strip consumes. A strip rated at 14.4 watts per meter draws 14.4 watts of power for every meter of length. Watts tell you how much electricity the strip uses, not how bright it is.
Higher wattage strips consume more power and generate more heat, which means they require appropriately sized power supplies and may benefit from aluminum profile mounting for better heat dissipation.
Lumens: Brightness Output
Lumens (lm) measure the total amount of visible light a strip produces. This is the actual brightness you perceive. A strip rated at 1000 lumens per meter produces twice as much visible light as one rated at 500 lumens per meter, regardless of how many watts each uses.
When comparing brightness between different strips, always compare lumens, not watts. Two strips can have the same wattage but produce very different lumen output depending on LED efficiency, chip quality, and design.
The Relationship Between Watts and Lumens
In general, higher wattage per meter does produce brighter light output. However, the efficiency of the LEDs determines how effectively watts are converted into lumens. A well designed, high efficiency strip might produce 120 lumens per watt, while a lower quality strip might only produce 80 lumens per watt.
This efficiency rating, measured in lumens per watt (lm/W), is a useful metric for comparing the quality and value of different strips. Higher lumens per watt means you get more brightness for less power consumption.
Wattage Range in Our Catalog
Our LED strips range from approximately 4.5 watts per meter on the low end to 20 watts per meter on the high end. Lower wattage strips (4.5W to 8W per meter) are well suited for accent lighting, shelf highlights, and decorative applications where subtle illumination is the goal.
Mid range strips (9W to 14W per meter) cover the broadest set of applications including under cabinet lighting, cove lighting, and general residential use. High wattage strips (15W to 20W per meter) deliver the brightness needed for task lighting, commercial displays, and primary room illumination.
How to Calculate Total Wattage
To find the total power requirement for your installation, multiply the strip's wattage per meter by the total length you plan to install.
Formula: Total Watts = Watts per Meter x Total Meters
Example: You are installing a COB strip rated at 10 watts per meter across a 6 meter kitchen cove. The total power draw is 10W x 6m = 60 watts.
Power Supply Sizing
Never size a power supply to exactly match your total wattage. Running a power supply at 100% capacity generates excess heat, reduces its lifespan, and leaves no headroom for power fluctuations. The standard practice is to add a 20% safety margin.
Formula: Required PSU Wattage = Total Watts x 1.2
Example: Continuing from the calculation above, 60 watts x 1.2 = 72 watts minimum. You would select a power supply rated at 75 watts or higher. A 100 watt power supply would be an excellent fit, providing ample headroom while remaining cost effective.
Full Project Example
Let's walk through a complete calculation. You want to install LED strip lighting under cabinets in a kitchen. The total run across all cabinets is 8 meters. You choose a 24V COB strip rated at 14.4 watts per meter with 1200 lumens per meter output.
Total wattage: 14.4W x 8m = 115.2 watts
With 20% margin: 115.2W x 1.2 = 138.24 watts
Power supply selection: Choose a 24V power supply rated at 150 watts. This provides clean headroom and ensures reliable, long term operation.
Total brightness: 1200 lm/m x 8m = 9,600 lumens across the installation, which is more than sufficient for kitchen task lighting.
Bottom line: Use lumens to compare brightness, use watts to calculate power requirements, and always add a 20% safety margin when selecting your power supply. Getting the math right upfront prevents flickering, overheating, and premature component failure.