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Tubular shapes

T5 bulb shape and size

T5 is the tubular lamp designation. Its nominal maximum diameter is 0.625 inches. T5 can refer to linear fluorescent/LED tubes or small incandescent envelopes. The base, voltage, light output, and exact overall length come from the individual lamp specification.

Representative family profile and nominal maximum diameter only. Overall length is not to scale, and the base is intentionally omitted.

Dimensions

What T5 tells you

Shape
tubular lamp
Nominal diameter
0.625 in (16 mm)
Typical bases
G5, E12
Common uses
linear fixtures, cabinet lights, specialty appliances

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 T5

  • T5 can refer to linear fluorescent/LED tubes or small incandescent envelopes.
  • Match length, base and ballast or wiring type.

Sources

Reference method

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