Lightbulbs

What's behind our lightbulb Ratings?

• Overall score
  Overall score combines life and rapid-cycle testing, brightness at 3,000 hours of use, and warm-up time performance.
• Type
  Whether the bulb is a CFL, LED, halogen (hlgn) or hybrid which is a combination halogen and CFL.
• Light color
  Actual 3K or 12.5K color temperature (kelvin) is the average measured color temperature of 10 bulb samples. Those with 2700 K are closest to incandescent bulbs; ones with 3000 K are similar to halogen bulbs.
• Claimed life
  Claimed life is how many years the manufacturer says the bulb will last based on 3 hours of use per day.
• Brightness
  Brightness indicates the brightness (lumens) of each bulb after 3,000 hours of life testing, as compared with the brightness of a comparable incandescent.
• Efficiency
  Efficiency is the comparison of the amount of light (lumens) produced by a given amount of electrical energy (watts). The more the lumens per watt the more efficient the bulb.
• Light distribution
  Measures how well a test bulb duplicates the light distribution of an equivalent incandescent bulb.
• Frequent on and off performance
  Frequent on and off performance testing reflects the average number of 2-minute on and 2-minute off cycles each bulb survived.
• Life testing
  Life testing reflects how many 3-hour on and 20-minute off cycles a bulb survives after 3,000 hours of the "on" cycle.
• Color accuracy
  The averaged measured color rendering of ten bulb samples. Those closer to 100 will better enable colors to appear the same as if viewed under the light of an incandescent bulb.
• Warm-up time
  Warm-up time is how long the bulb took to reach near full brightness. Bulbs that take 0 to 15 seconds to reach near full brightness scored excellent. Those taking 16 to 31 seconds scored very good, 32 to 46 seconds are good, 47 to 62 seconds are fair, and over 63 seconds scored poor.
• Works with dimmer
  Manufacturer claims that bulb is dimmable.
• Works with fully enclosed fixtures
  Manufacturer claims that bulb can be used in a fixture that completely encloses the bulb.