If you are shopping for smart light bulbs 💡 you may have seen a choices you did not expect.  Specifically, we had one client looking for LED light bulbs that would work with Google Assistant and a month before that we had a different client looking for smart bulbs they could control using Amazon Alexa mini smart speaker , so we decided to spell it out.

what do codes mean google assistant amazon alexa smart bulb e26 vs e27 vs e22It turns out that these codes have been around for decades and have nothing to do with smart bulbs.  The codes denote the size and the type of connector.

A common full specification for a light bulb contains six things:

  1. Lighting technology: i.e. incandescent, LED, CFL, Halogen…
  2. Wattage: electricity consumption which translates to brightness
  3. Bulb Diameter: How fat is the bulb
  4. Diffuser Filter: what ‘color’ is the light
  5. Connector: screw, bayonet or two post “GU”
  6. Connector Diameter: how big is the screw or bayonet

bulb base fittings explained

In Canada and United States “normal” household bulbs are now standardized on:

  1. LED
  2. 9 Watt
  3. A19
  4. Cool white
  5. Screw bulbs
  6. with base diameter of 26 or 27

Where as in the UK, Europe and parts of Asia bayonet connectors are widely used in households.

Fun Fact: When you see the letter E, it stands for Edison, yes that Edison.  Thomas Edison is credited with inventing the light bulb and when he lost control of Edison labs, the famous JP Morgan amalgamated it with a number of other companies working with electricity and called it General Electric.  However, the name “Edison Screw” has persisted.  Watch The Current War on Netflix if you find this interesting.

But I digress… Here is an easy reference for which light bulb type is used in major markets:

  • Australia: E27 Screw (or B22 Bayonet Cap)
  • Canada: E26 Screw
  • Europe: E27 Screw
  • Japan & Taiwan: E26 Screw
  • United Kingdom: E27 Screw (or B22 Bayonet Cap)
  • United States: E26 Screw

However, that does not mean Americans and Canadians have no bayonet bulbs.  In fact, if you have an older car, it is full of them and many track lighting solutions (like you might have in your kitchen) use those easy to push in and twist bayonet bulbs.

anatomy of a light bulb code

There are other specific to consider.  For instance the:

  • Smart: can it be controlled by Google Assistant, Siri, Alexa, …?
  • Lumens output: brightness – its not all about wattage
  • Bulb shape: A19 is the common round bulb we all know and love
  • Life expectancy rating: an LED bulb should last at least 10,000 hours
  • Dimability: not all bulbs can be used with dimmers
  • Colors changing: this is new to LED bulbs, many bulbs can now change colors

If you want to know everything a non-engineer would ever want to know about light bulb specifications, read this article.


vera pistel · January 11, 2022 at 12:36 pm

What is the E22 base type?

    Ian Matthews · January 19, 2022 at 8:35 pm

    That would be EDISON 22 which means screw base that is 22mm in diameter.

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