Saab 99 License Plate Bulb Size

The Saab 99 license plate light uses a bulb with the specific 12821 identification for the rear illumination system. Data for the lighting component covers the period from 1975 through 1980.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1975-1980	12821

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12821

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Additional Notes

The Saab 99 uses the 12821 bulb across all listed model years, spanning 1975-1980.
The 12821 is a Philips part number designation for a miniature wedge bulb.
This bulb follows the T10 form factor, a common wedge-style lamp widely used in automotive interior and exterior lighting positions.
The base type is W2.1x9.5d, which refers to a wedge base with a 2.1mm wire width and a 9.5mm insertion depth, held in place by friction rather than a twist-lock or bayonet mechanism.
The 12821 operates at 12 volts, consistent with the standard electrical system voltage found in passenger vehicles of this era.
The bulb carries a 5-watt power rating, typical for low-intensity applications such as license plate illumination.
The T10 wedge base format means the 12821 is physically interchangeable with other T10-based bulbs sharing the W2.1x9.5d base, provided voltage and wattage ratings are also compatible.
When substituting bulbs, wattage must remain within the tolerance of the original socket and wiring, as exceeding the rated wattage can cause heat damage to the lens housing or socket.