How to Choose an LED Light Bulb
Match the base, physical shape, fixture rating, and location first. Then choose brightness in lumens, appearance in kelvins, suitable color rendering, dimmer compatibility, beam pattern, and the lowest reasonable wattage that meets those requirements.
What to know
- Lumens measure brightness; watts measure electrical power use.
- A physically fitting bulb can still be unsafe or short-lived in an enclosed, damp, wet, or high-temperature fixture.
- A dimmable LED can perform poorly with an incompatible dimmer.
- Read the FTC Lighting Facts label and verify safety certification when the manufacturer or seller is unfamiliar.
The direct answer
Choose an LED bulb in this order:
- Correct base.
- Correct physical shape and size.
- Approved for the fixture and location.
- Desired brightness in lumens.
- Desired color temperature in kelvins.
- Adequate color rendering.
- Compatible dimming behavior.
- Appropriate beam pattern.
- Reasonable energy use.
- Traceable safety certification and warranty.
Do not shop by the old incandescent watt number alone. The Federal Trade Commission says lumens measure brightness while watts measure energy use. [1]
Start with the base
Common household bases include E26 medium screw, E12 candelabra, GU10 twist-lock, GU24 two-pin twist-lock, and several bi-pin formats.
Bring the old bulb or photograph its markings. Do not force a base that appears nearly correct. Electrical contacts and mechanical retention depend on the exact format.
Check shape and dimensions
A bulb can have the correct base but fail to fit beneath a glass globe, recessed trim, narrow shade, appliance cover, or weatherproof enclosure.
Record overall length, widest diameter, neck shape, and whether the fixture needs an omnidirectional or reflector bulb.
Common shapes include A19, BR30, PAR, globe, candle, and tubular bulbs.
Buy brightness in lumens
The FTC Lighting Facts label emphasizes lumens because bulbs can produce similar light using very different wattages. [2]
Familiar rough comparisons include:
- About 450 lumens for the traditional 40-watt incandescent range.
- About 800 lumens for the traditional 60-watt range.
- About 1,100 lumens for the traditional 75-watt range.
- About 1,600 lumens for the traditional 100-watt range.
Use these as references rather than guarantees. Fixture design, shades, reflectors, wall colors, and placement change how much useful light reaches the room.
Choose color temperature
Color temperature is listed in kelvins.
Common ranges include:
- 2200K to 2700K: very warm to warm.
- 3000K: warm-neutral.
- 3500K: neutral.
- 4000K: cool-neutral.
- 5000K: daylight-like.
Lower kelvin numbers are not dimmer. They describe warmer color.
For a multi-bulb fixture, buy the same color temperature and product family when visual consistency matters.
Check color rendering
Color Rendering Index, or CRI, describes how colors appear under a source compared with a reference source of similar color temperature.
Higher CRI can be useful in kitchens, closets, art areas, makeup spaces, fabric work, wood finishing, and food presentation.
CRI does not capture every aspect of color quality, but it remains a useful screening specification.
Dimming compatibility
A bulb labeled dimmable can still behave badly with an incompatible dimmer.
Symptoms include flicker, buzzing, narrow dimming range, sudden shutoff, failure to start at low settings, and different bulbs responding differently.
Check the bulb manufacturer’s compatibility list, dimmer model, number of bulbs, minimum and maximum load, and whether the dimmer was designed for LED loads.
Do not place a non-dimmable bulb on a dimming circuit.
Enclosed fixtures
LED electronics produce heat even though the bulb uses less electricity than an incandescent source.
A bulb not approved for enclosed fixtures may overheat when trapped beneath a sealed globe. Look for wording such as suitable for enclosed fixtures or not for use in enclosed luminaires.
Also check for damp-location, wet-location, appliance, emergency-lighting, and high-temperature restrictions.
The label controls. Physical fit is not a thermal rating.
Directional bulbs and beam angle
BR and PAR bulbs direct light rather than spreading it uniformly.
A narrower beam concentrates light on artwork, counters, displays, or work surfaces. A wider beam covers more area.
Match beam angle to fixture spacing and ceiling height rather than buying every recessed bulb with the same generic description.
Read the Lighting Facts label
The FTC label can report brightness, estimated yearly energy cost, life, light appearance, and energy used. [2]
The annual cost uses standardized assumptions. Your result depends on electricity price and operating hours.
Certification and warranty
Look for a legitimate testing-laboratory mark and verify it in the laboratory’s directory when the product or seller is unfamiliar.
Also compare warranty length, proof-of-purchase requirements, manufacturer identity, replacement process, and fixture suitability.
A 25-year life claim based on three hours per day does not mean continuous kitchen operation is guaranteed until 2051.
Bottom line
Match the base, dimensions, fixture rating, and location before choosing appearance.
Then buy brightness in lumens, select color temperature and CRI, verify dimmer compatibility, and compare energy use. Watts tell you what the bulb consumes, not how bright it will be.
Limits and cautions
- Actual room brightness depends on fixture design, shades, reflectors, surface colors, and placement.
- Color rendering cannot be reduced to one number for every visual task.
- Dimmer compatibility and enclosed-fixture suitability are product-specific.
Source notes
- Shopping for Light BulbsFederal Trade Commission
- FTC Lighting Facts Label: Questions and Answers for ManufacturersFederal Trade Commission
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