Dimensions
What A25 tells you
- Shape
- extra-large A-shape bulb
- Nominal diameter
- 3.125 in (79 mm)
- Typical bases
- E26, E39
- Common uses
- high-output fixtures, commercial pendants
The diameter is part of the naming system, not a full dimension drawing. Individual models can differ in overall length, neck profile, optics, and manufacturing tolerance. Use the maker's drawing when the fit is close.
At the fixture
Four other details to record
- Read the base code and voltage on the old lamp or fixture label.
- Compare the published maximum diameter and overall length with the available space.
- Record lumens, beam angle where relevant, color temperature, and dimming behavior.
- Look for the enclosure, location, temperature, or vibration rating required by the fixture.
Easy to miss
Notes for A25
- Base and overall length vary by product.
- Large lamps need a fixture clearance check.
Sources
Reference method
BulbMatch uses the U.S. eighth-inch naming convention as a nominal shape reference and keeps model-specific dimensions separate.