When you buy a light bulb, it is not as simple as it used to be. You can't just pick up any light bulb and expect that it will work with the other light bulbs in your room or even in your fixture. So before you purchase your next bulb, make sure you know these five things.
Check your bulb base size and bulb shape
Light bulbs come in many different shapes and sizes. One kind of light bulb used in the U.S. is called an A19, with a screw base on the bottom (E26). The E means that it has an Edison Screw and it is 26mm across (in Europe you will find E27 bulbs). Another type of light bulb is what we all think of when we envision what a light bulb looks like: A for arbitrary, shaped like what we imagine a light bulb to be.
If you wonder what bulb size is my car takes, just take a look under the hood. Most cars have a sticker that specifies what kind of bulbs they need and what size they are.
Determine much light you need
Instead of watts, look for the number of lumens when you are looking for a replacement bulb. Watts measure how much energy a bulb uses, but lumens measure how much light a bulb produces. You'll usually also see a watt equivalent, but to be sure, look for the lumens.
Your house has a limit to how many watts it can handle. If you buy a more energy efficient light bulb, but want brighter lights, you can buy a higher wattage light bulb and stay within the limit. For example, if your new light is 9-watts and you have no other lights on in your house then 15-watts should be safe.
Select the right color of white for your light bulb
White light bulbs have a color cast. This means that they can give off different colors depending on the kind of light bulb. You might have a light bulb that gives off a yellow light, a cool blue light, or something in between. Some manufacturers call this "soft" or "warm" or "daylight."
But these terms aren't standard across all manufacturers. To figure out what kind of replacement light bulb you need, you should look at the color temperature. This is measured in degrees Kelvin.
Some LED lights can change their color to different types of white light. This might be interesting to you if you want a specific type of light for a specific task.
For example, you might want a bright light in the morning or when you are reading, but a warmer light at bedtime. Blue light has been shown to interfere with sleep, so it is a good idea to have lights that you can adjust to warmer tones at night.
Finally, some light bulbs don't show the true colors of an object. This is measured on a scale from zero to 100. Incandescent and halogen bulbs have a perfect CRI of 100. As long as a compact fluorescent or LED bulb has a CRI of 80, it's considered good, and over 90 is regarded as excellent.
Choose the right type of light bulb
When you are looking to buy new light bulbs, look for the Energy Star label. This means that the bulb has been tested and meets energy efficiency standards. The label will tell you how bright the bulb is (measured in lumens), what color it is, how long it will last, how much energy it uses, and how much it costs to run for a year. This makes it easy to compare different types of bulbs.