Buying LED bulbs: What to look for
Inefficient light bulbs – like incandescents and fluorescents – are being phased out for LEDs. To get the right LED, you’ll need to know how to pick the right brightness, color and bulb type for your home.
The lightbulb aisles in U.S. stores are about to look (slightly) different. In 2022, the Department of Energy (DOE) adopted energy efficiency requirements that will all but ban incandescent and many fluorescent bulbs, and make LEDs (light-emitting diodes) the default option for most of us. That’s great, because LEDs are much, much more efficient than incandescent and even fluorescent bulbs. In fact, the DOE estimates that if the U.S. fully adopted the most efficient LEDs, America could save the equivalent of 20% of all the electricity used in U.S. buildings in 2018. Switching to LEDs means you’ll use less energy and reduce your utility bills. It also means less need for fossil fuel power plants, reducing the damage to our health and environment.
LEDs are quite different from incandescent and fluorescent light bulbs – in most ways, far better – but there are some things you need to know to enjoy their lighting benefits in addition to their energy and cost savings. From brightness to color, LEDs provide as much or more choice and control over your lighting as incandescents and fluorescents. There are even “smart” LEDs you can even control from your phone, adjusting color, brightness, schedules or even syncing them to music. Here are some tips to help you pick the right bulb.
What are lumens? The brightness of the LED
The first metric to know about when buying LED bulbs is lumens. Lumens are a measurement of brightness (more lumens = higher brightness), and the first thing you should look for to decide if a given LED will meet your needs.
Less-efficient bulbs, like incandescents and fluorescents, get brighter as they use more power (which is why we often describe the brightness of incandescent bulbs in watts, a unit of power).
LEDs, on the other hand, don’t necessarily require more power to be brighter, so they are measured with lumens. Manufacturers are required to label LEDs with their brightness in lumens, so this should be easy to find on the box. Before buying an LED, take note of the wattage of the incandescent bulbs you’re replacing, and think about whether you want the space to be lit more or less brightly.
The Department of Energy has compiled a rough guide of LED brightness and how it compares to incandescents based on watts:
- What LED bulb is equivalent to a 100-watt incandescent?
- An LED rated at 1,600 lumens should produce light as bright as a 100-watt incandescent lightbulb (think brightly lit spaces like offices or kitchens).
- What LED bulb is equivalent to a 75-watt incandescent?
- An LED rated at 1,100 lumens should produce light as bright as a 75-watt incandescent.
- What LED bulb is equivalent to a 60-watt incandescent?
- An LED rated at 800 lumens should produce light as bright as a 60-watt incandescent (think lamps and other, softer home lighting).
- What LED bulb is equivalent to a 40-watt incandescent?
- An LED rated at 450 lumens should produce light as bright as a 40-watt incandescent.
What is Kelvin? The color of the LED
The second, crucial aspect of LEDs is their color. While incandescent bulbs are yellow and warm (because, remember, they’re literally glowing with heat) and fluorescent bulbs are generally made to be somewhat yellow, LEDs can come in a much wider range of colors. This gives you much more control over the light and color you want, but it can be confusing, since the other technologies don’t have these options. Kelvin (abbreviated K) is the way the color of LEDs is specified, with lower Kelvin values meaning light that is warmer (more yellow and orange) and higher Kelvin values indicating cooler, bluer light. CNET, Philips, GE and others have guides to choosing the right color of light, but in general:
- For a warm, amber-y light (like in a den or living room with the lights down low), look for 2,200K or 2,300K LEDs.
- For a soft yellow-white light (dining room, living room, bedroom), look for 2,700K-3,000K LEDs. This is the typical color of incandescent light, with 3,000K being on the cooler end of things.
- For white light, with just a little yellow in it (kitchen, bathroom), look for 3,000K-4,000K LEDs.
- For bright white light, like for an office, look for 4,000K-5,000K LEDs.
- For “daylight” (which is much bluer than most indoor lighting, provides high color contrast and is not necessarily preferred for most home uses), look for LEDs above 5,000K.
In addition to listing brightness (in lumens) on LED packaging, manufacturers are required to show LEDs’ color (in Kelvin) on the box. Make sure you know where you’re going to put the bulb and what you want to use that space for, and/or try some of the LEDs whose color you can control from a smartphone.
What is color-rendering index? How things look in the light
Color-rendering index (CRI) is a measure of how the light from a bulb affects the appearance of colors of illuminated objects. CRI is measured on a scale from 1 to 100, with higher values indicating that objects will look more like they do under natural sunlight. Manufacturers are not required to publicize the CRI of an LED, though they often do, and it isn’t always the most useful or reliable data point because it is based on a small number of color samples and the results are averaged (there are potentially better standards in the works). Though you can’t rely on CRI too much, look for higher CRI values if possible (above 90 is better) and consider checking customer reviews for comments about color rendering.
Questions to ask when buying LEDs
LEDs are not a new technology, but their use for space lighting (versus just as indicator lights) is relatively new, and the technology is quickly evolving and improving even as prices drop. When buying LEDs, there are some things to be aware of, and some problems people sometimes encounter, especially because LEDs are replacing an existing technology (incandescents and fluorescents) and are being swapped into existing systems.
Why are LED bulbs better than incandescents and fluorescents?
- Incandescent bulbs are essentially small space heaters that happen to emit some light as a byproduct. They run electricity through a thin filament, and the electrical resistance of the filament causes it to heat up and glow, producing some light. That’s why incandescent bulbs use so much more power (watts) than LEDs.
- Fluorescent bulbs pass electricity through gaseous mercury (a highly toxic element known to cause weakness, muscle atrophy, trembling, changed nerve function, changed mental function, kidney damage, and respiratory damage) which then emits ultraviolet (UV) light that is converted into visible light by powdered substances that glow when exposed to UV. They are more efficient than incandescent bulbs, but present health and environmental risks because of the mercury.
- LEDs – or light-emitting diodes – pass electrons in one direction between two different kinds of semiconductors (similar to what makes up transistors in electronics), producing light. They generate much less heat, produce light more efficiently, and can last much longer than either incandescents or fluorescents.
Can I dim my LED bulb?
There are lots of different kinds of dimmer switches that you might have in your home, from those that vary voltage to those that flick power on and off rapidly and many others. While incandescent bulbs generally work with all different types of dimmers, LEDs are more complicated: for example, they have a minimum voltage needed to function at all, and are not always built to handle rapid on-off cycles. LEDs can be made to be dimmable, but aren’t always compatible with every type of dimmer.
“Smart” LEDs (whose color and brightness can be controlled by a remote or a smartphone) are generally not compatible with any kind of dimmer. When an LED is used in an incompatible dimmer circuit, it can flicker, hum, buzz, not work below certain thresholds, or have a significantly reduced lifespan.
If you’re getting LEDs for a house or room without dimmers, you can get whatever bulb you want, but if you want to be able to dim your LEDs, the following tips can help you avoid problems:
Tips for buying dimmable LED bulbs
- If you know what kind of dimmer switches you have, look for LEDs labeled “dimmable” that are compatible with that type. Buy one LED from a well-known brand that should be compatible, and test it out. You may be able to return it if it doesn’t work (and check whether you can do so when you buy it).
- If you don’t know what kind of dimmer you have, you can try a variety of LEDs compatible with different types (see above).
- You can also replace the dimmer switches you have with models designed specifically for LEDs. Search around for recommendations from organizations/reviewers you trust.
- As a last resort, you could try buying so-called “smart” LED bulbs that can be controlled with a remote or your phone. While they don’t work with dimmer switches, they have built-in circuitry to allow dimming from the remote or on an app. Plus, they often can change colors. You may not end up using the color-changing or dimming features of a smart bulb all that often, and some people don’t like having to use their phones or a remote to control their lights, but it is an option.
Can I put an LED into any type of fixture?
While LEDs produce much less heat than incandescent or fluorescent lights, they do produce some. Basic LEDs are designed, however, to conduct that heat towards the base of the bulb and dissipate it from there (whereas, say, an incandescent bulb dissipates heat from the bulb itself). That means that if there is no way for the base of the LED to dissipate heat (e.g., if it’s in an enclosed fixture like a fully enclosed porch lamp or a recessed dome light), it could overheat and burn out. Luckily, some LEDs are designed to be used safely in enclosed fixtures. To avoid overheating problems, for any enclosed fixtures – recessed dome lights, enclosed porch lights, or any other fixture where there won’t be a lot of ventilation or heat dissipation – use LEDs that are designed for enclosed fixtures.
Should I buy fixtures with built-in LEDs?
Some LED fixtures are sold with bulbs that are neither removable nor replaceable. That can make them easy to install, but it means that the whole thing becomes non-functional or much less useful if even a single piece stops working. That means you might end up getting rid of pieces that are perfectly good and replacing more than is necessary, which is a waste of your money and of energy and resources. If possible, try buying LED bulbs to go into your current fixtures, or buying fixtures with replaceable bulbs.
How much power will an LED use?
Any LED bulb you find will likely use a lot less power than the incandescents and fluorescents you’re used to. That being said, there is still variation in power consumption between LEDs. If you’re deciding between two different LED bulbs that are equivalent in lumens, Kelvin and CRI (and, if you’ve tried to dig further, customer reviews), you may want to go with the bulb that uses less power (measured in watts), as that means you’ll use (and pay for) less electricity.
Some people have noticed other problems, such as LEDs that don’t last as long as they were promised (though this might be an issue with overheating, see above), or LEDs that change color as they age and degrade. But as the technology improves, and as we get more used to the differences between LEDs and the bulbs we’ve been using, LEDs are only going to get better. That means energy and cost savings for you, pollution savings for the planet, and much more control over how you light up your life.
Policy Analyst, Frontier Group
Bryn Huxley-Reicher is a policy analyst at Frontier Group focusing on issues related to clean energy and the new economy. He has a BA in applied mathematics focused in earth and planetary sciences from Harvard University.
Senior Director, Campaign for 100% Renewable Energy, Environment America
Johanna directs strategy and staff for Environment America's energy campaigns at the local, state and national level. In her prior positions, she led the campaign to ban smoking in all Maryland workplaces, helped stop the construction of a new nuclear reactor on the shores of the Chesapeake Bay and helped build the support necessary to pass the EmPOWER Maryland Act, which set a goal of reducing the state’s per capita electricity use by 15 percent. She also currently serves on the board of Community Action Works. Johanna lives in Amherst, Massachusetts, with her family, where she enjoys growing dahlias, biking and the occasional game of goaltimate.