It seems simple enough: You want brighter light, you buy a higher wattage bulb, right? Wrong. It’s time for a lesson on watts vs. lumens
What’s a Watt?
Watts are the measurement units of power consumption. (And, since they determine the rate of energy consumption, they’re an indication of the running cost of a lighting system.) For example, a traditional incandescent bulb requires a higher wattage for brighter light—because it takes more energy to create it. Often, you’ll see notes on an LED fixture indicating the equivalent incandescent wattage. Because LED lights take less energy to make more light, you may find a 10-watt LED bulb that delivers the same lighting output as a 60-watt incandescent bulb.
Lumens are the measurement units of total lighting output—or, simply put, the brightness of the bulb. When you want a brighter light, you opt for more lumens. Just one note: Light bulbs don’t always radiate lumens uniformly in all directions, so they may appear brighter from some angles than from others. Before purchasing a lamp or fixture, ask a FLOS expert to make sure you get the desired lighting distribution.
Luminous efficacy is the ratio of lumen output to watts consumed. Think of it like the miles per gallon measurement in a car: a higher MPG value makes a car more economical, just like a higher lumens per watts value makes a lighting fixture more efficient.
Most LED lights exceed 100 lm/W, while incandescent lights are typically in the range of 10-20 lm/W.