When we bought our house, the lighting fixtures in the ceiling came with R20 bulbs. I know nothing about lighting so I figured that only R20 bulbs are compatible with our fixtures. But I'm realizing that may not be the case.

So what are kinds of bulbs can I use that are interchangeable with R20 bulbs?

More specifically, I'm interested in Philips' Hue bulbs

Are any bulbs from that line compatible with lighting fixtures that accept R20 bulbs?

1 Answer 1


These would be the equivalent of an R20 flood lamp: enter image description here

R20 is simply a lamp size and style designation. R for reflector lamp. 20 for 20 eights of an inch, or 20/8", or 2.5" in diameter.

Just know, standard "A-lamps" will fit similarly to R20 lamps. It's just R lamps are reflector and will concentrate the light basically in one direction, while A lamps glow all around. The design of the fixture will determine what lamps will work best.

  • @KhoiVinh And of course observe the fixture wattage limits.
    – derobert
    Commented Dec 11, 2014 at 22:49

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