Printable bulb-base measuring guide

Print and check the scale

1. Choose 100% or Actual Size in the print dialog. Turn off Fit to Page.
2. Measure the red calibration line with a physical ruler. It must be 50 mm.
3. Switch off and unplug the fixture where possible, then remove the cooled bulb.
4. Measure straight across the widest outside part of the metal thread.

The drawing compares nominal code diameters. It is not a manufacturing-tolerance gauge and does not confirm voltage or compatibility.

Reuse

You may reuse the unmodified chart in an article, repair guide, classroom handout, or forum answer with a visible link to getbulbmatch.com/bases/. Do not remove the safety note or present the chart as an electrical compatibility test.