Lumens vs Watts – what LED bulb should you pick to replace an incandescent?

I can never find this info when I need it, and I’m terrible at remembering numbers so I decided to post it here for everybody’s edification.  Incandescent bulbs are going away. Many governments are prohibiting their manufacture, so it’s only a matter of time.  Replacement choices are either CF (compact fluorescent) or LED.  These bulbs have a light output rated in Lumens, so it’s good to know what the Lumen equivalent is if you are replacing a 60W incandescent bulb and want the same amount of light.

  • 40-watt incandescent bulb = 450 lumens
  • 60-watt incandescent bulb = 800 lumens
  • 100-watt incandescent bulb = 1600 lumens

Many CF bulbs have a slow start-up time, so it can take up to 2 minutes for the bulb to reach full brightness.  If this is undesirable, then opt for an LED bulb as they are instant-on.  LED also is lower heat and has less power draw, but can be more expensive than CF bulbs.

The other wrinkle is color temperature.  We’re all familiar with “cool white” or “warm white” bulbs, but translating that into LED or CF specs on the packaging can be daunting.  Here’s a handy chart that shows the Kelvin temperatures and the common vernacular equivalents.

As you can see, a cool white bulb is around 4200K, so when shopping for a replacement for a 100W cool white incandescent, you would want to buy a 1600 lumen 4200K bulb.


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