Been using the A19 bulb shape my whole life for things like fixtures & lamps. But is it okay to use different shaped bulbs as long as the base is the correct version?

I always presumed if a lamp has a E26 base, I must use an A19 bulb. Is this true?

2 Answers 2


No problem at all as long as:

  • The bulb doesn't touch the fixture (except the base, of course)
  • Heat is dissipated properly. Usually not a problem as newer CFL and Led bulbs often use far less power and generate far less heat than the fixture can handle
  • I use incandescents! In a lamp is that bad? :-(
    – verve
    Jan 22, 2019 at 22:36
  • Waste of energy. But otherwise ok. Typically older fixtures are rated for incandescent but bottom line is stay at or below whatever wattage is marked on the fixture. If you're not sure then assume 60w max per bulb. Jan 22, 2019 at 22:53

Depends on what you mean by "any shape", there are not that many, and it also depends on the fixture design. If you are referring to "flame" shaped decorating bulbs, then yes, absolutely, unless the fixture is a table lamp that has a clamp-onto-the-bulb shade. But spot or flood reflectors type bulbs, or large globe type bulbs may interfere with air flow, depending on your fixture design.

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