Guides

Car Bulb Numbers Explained

By Fit My Parts · Published October 20, 2026

Car bulb numbers identify the base, filament and size, so any bulb with the same number fits the same socket regardless of the car. Owner's manuals print them in one of two systems: US trade numbers (194, 3157, 7443, 9005) or ECE categories (W5W, P21/5W, H11).

The most listed bulb numbers

These are the bulb numbers printed in the most model-year manuals on this site:

Headlamp capsules

H-series numbers (H8, H9, H11, H16) and the 9000 series (9005, 9006, 9012) are halogen headlamp and fog capsules. H11 is the most common low beam in these manuals, and 9005, also called HB3, the most common high beam. HID cars print D-series codes such as D4S instead, and LED headlamps print no bulb at all because the lamp is replaced as a unit.

Wedge and twist-socket bulbs

W5W and 194 are small glass wedge bulbs for side markers and plates. 7440, 7443 and 3157 are larger bulbs for turn, stop and reverse lamps; a 7443 or 3157 has two filaments (tail and brake). The suffix tells the colour or life: NA is amber, while K, A and LL variants are long-life versions of the same base.

Finding yours

Open your car under Cars and the bulb table lists every exterior position with the manual page. The bulb index lists every bulb number on the site with the cars that use it. When a car's manual shows two systems side by side, as Mazda does, that pairing is copied; this site does not add cross-references the manuals do not print, because that is where most bulb number mix-ups start.

Sources

• Bulb numbers: each car's official owner's manual, cited with its page on the car's page.