How many generations does it take to change a lightbulb joke?

Is this the end of lightbulb jokes? With a claimed life of 18 to 46 years, LED bulbs may only have to be changed once every generation—or two. So in the future when someone is asked, "How many [fill-in-the-blanks] does it take to change a lightbulb?" the answer might be, "You mean you have to change lightbulbs?" Consumer Reports is trying to answer that questions in its first full test of LEDs.

Most of the LEDs we recently tested were impressive, and when 19 staffers tried the bulbs at home, they liked them and favored some over others. But our testers also said they wouldn't buy LEDs until prices dropped. The bulbs in our labs cost $20 to $60 each. Our tests found they can take four to 10 years to pay for themselves. But even at those prices, you can still save $65 to $400 in energy costs over the life of the LED, compared to an incandescent.

Some of our Facebook followers have asked questions about performance. We tested 10 different LEDs, 100 bulbs total, including ones for table and floor lamps, indoor downlights, outdoor floodlights, and porch/post lights. After 3,000 hours of testing, energy use matched or exceeded claims and frequently turning them on and off didn't affect them. No one brand was consistently high performing across the different bulb types. Some LEDs are dimmable and dimmed as low as incandescents. Most LEDs are in the 2700 to 3000 Kelvin range, meaning the light's color is warm like an incandescent's. Our lightbulb Ratings provide important information on brightness, warm-up time, and light distribution and, of course, note which are standouts.

And that brings us back to the question of how long LEDs really last. The claims range from 20,000 to 50,000 hours. Nearly all the LEDs we tested are still burning brightly after 3,000 hours; only four stopped working. And two Cree LEDs we turned on over a year ago have been burning nonstop for more than 9,000 hours. Our tests continue, and we'll continue to update you in the months and years to come.

—Kimberly Janeway