Those who go shopping for new light bulbs for the first time often wonder why there is such a wattage difference between different bulbs. An old-fashioned light bulb might have 60 or 100W, but a LED bulb right next to it might have only 10W. Why is that? Well, as the LEDs are far more efficient, they need less power to be as bright as the traditional light bulbs. All in all, it’s good to know the equivalent wattage for LED bulbs to get the desired amount of light.
What’s the Difference Between LED Lights and Traditional Light Bulbs?
Ever since the late 19th century, people have been using the same type of light bulb — the incandescent tungsten bulb. It works by heating up a thin strand of metal (usually tungsten) inside a glass bulb. However, most of the energy used to power the bulb radiates out as heat. Only around 5% of the electrical energy converts to light. In addition, the high heat of incandescent light bulbs shortens their lifespan to about 1,000 hours.
Then, in the 1980s, fluorescent lights became compact enough to fit in a light bulb fixture. They’re about three times as efficient as traditional light bulbs and they last for about 10,000 hours. However, the light they produce is cold and harsh. Also, they contain mercury, which is extremely toxic. In fact, some countries have banned CFL lighting and so far, commercial production has mostly stopped.
Finally, LED lights became the most popular form of lighting in the 2010s. Compared to the traditional bulbs, LEDs are ten times as efficient, converting more than 50% of the electrical energy into visible light. On top of that, specialized lights can convert around 80% of energy into light. In addition, LEDs can last up to 20,000 hours, since they produce a minimal amount of heat.
How to Calculate the Equivalent Wattage for LED Bulbs, CFL Bulbs, and Incandescent Bulbs
The best way to compare different types of light bulbs is not to use wattage, but luminosity. Each light bulb, regardless if it’s LED, CFL, or incandescent, has a lumen rating on the package. For example, a 60W traditional light bulb produces around 800 lumens of light. For the same amount of light, you’ll need a 5–10W LED, depending on the bulb’s color temperature. Since producing warm light requires more energy than producing cool light, warm LED bulbs are usually slightly less efficient than cool ones.
Nowadays, LED light manufacturers print out their own estimates of equivalent wattage. However, they can get a bit generous at times, so you should always check the lumen rating. For instance, a 15W LED light will produce around 1,500 lumens, which is equivalent to about 100W incandescent. Still, some manufacturers will promote it as 150W to try and trick you.
For most indoor applications, you need about 20 lumens per square foot of area. However, objects such as furniture, shades, light fixtures, etc. might bump the number up by 10–20%. So, if you want to light up a 200 square feet space, you’ll need 4–5,000 lumens, depending on the layout. For that amount of light, you’ll need 5–6 60W incandescent light bulbs. On the other hand, the equivalent wattage for LED bulbs to achieve the same result is around 50W.