What Bulb For

Bulb codes and brightness

What the codes on a bulb mean, how to tell its base, how bright it is and what color its light is.

Bulb codesA19 is the glass shape and size; E26 is the screw base. A chart and a PDF. Identify the baseTell a bulb's base by its look: screw (E26, E12, E17), two pins, or push and twist. Watts to lumensConvert old bulb watts to lumens and back, and check a fixture's wattage limit. Fixture max wattageWhether an LED fits a fixture's wattage limit, from the Energy Used on its label. Light color (kelvin)What 2700K, 3000K, 4000K and 5000K look like, and the names on the box. How long LED bulbs lastWhat the hours and years on an LED's box mean, and how long they last if the light stays on. Broken CFL cleanupThe EPA's steps for cleaning up a broken CFL or fluorescent tube, in its own words. Light bulb disposalWhere CFLs, fluorescent tubes, LEDs and old bulbs go when they're done, and why local rules decide. Running costWhat a bulb or device costs to run a day, a month and a year, and what an LED saves. Light left onWhat a light left on costs a day and a year, old bulb or LED, at your own rate. Space heater costWhat an electric space heater costs to run an hour, a day and a month, from the watts on its label.

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General guidance from manufacturer and standards data. Products vary, so check the label and the maker's instructions.