How to identify G9
- Look for two U-shaped wire loops at the bottom.
- The pin system is visually different from the straight pins on G4.
- Check the printed voltage and wattage on the old capsule.
Where it is commonly used
Common use is a clue, not proof. The fixture label and model documentation take priority over a visual match.
Bulb shapes sold with this base
You may see these shapes with a G9 base. The base code does not guarantee the bulb width, length, beam angle, or clearance.
Before you buy a replacement
- G9 LEDs can be larger than halogen capsules.
- Confirm the LED is rated for a fully enclosed fixture when applicable.
- Allow a halogen lamp to cool completely before removal.
Quick answers
Questions about the G9 bulb base
What is a G9 bulb base?
A G9 bulb base has two U-shaped wire loops with nominal 9 mm center-to-center spacing. It pushes straight into the socket; voltage and capsule dimensions must be checked separately.
What size is a G9 bulb base?
G9 has a nominal 9 mm pin spacing. Pin spacing is measured from the center of one pin to the center of the other. Use the printed base code when available because a visual estimate is not conclusive.
Where is a G9 bulb base commonly used?
Common examples include vanity lights, wall sconces, decorative pendants, compact fixtures. Fixture type is only a clue; confirm the code on the bulb, socket, fixture label, or manufacturer documentation.
Can I choose a G9 replacement by appearance alone?
No. Match the G9 connection first, then verify voltage, actual input wattage, bulb dimensions, fixture restrictions, controls, and any enclosure or location rating required by the installation.
Is G9 a bulb size or a base?
G9 identifies the loop-pin base and its nominal 9 mm pin spacing. The capsule width, length, voltage, and light output vary by model.
Can a G9 halogen bulb be replaced with LED?
Often, but G9 fit alone is not enough. Match the marked voltage, compare lumens and physical dimensions, and verify dimmer, enclosed-fixture, and location ratings for the exact LED model.