PAR38 bulb shape and size

Dimensions

What PAR38 tells you

Shape

large PAR reflector bulb

Nominal diameter

4.75 in (121 mm)

Typical bases

E26

Common uses

outdoor floods, security lights, large recessed cans

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

1. Read the base code and voltage on the old lamp or fixture label.
2. Compare the published maximum diameter and overall length with the available space.
3. Record lumens, beam angle where relevant, color temperature, and dimming behavior.
4. Look for the enclosure, location, temperature, or vibration rating required by the fixture.

Easy to miss

Notes for PAR38

• Verify wet-location rating for exposed outdoor fixtures.
• Beam angle can change the useful coverage substantially.

Sources

Reference method

BulbMatch uses the U.S. eighth-inch naming convention as a nominal shape reference and keeps model-specific dimensions separate.

• LEDVANCE guide to light bulb shapes, types, and sizes
• U.S. Department of Energy: lumens and lighting choices