Austin Healey Sprite License Plate Bulb Size

The Austin Healey Sprite license plate light uses bulb sizes 57 and 257 according to the provided specifications. The data covers the range from 1958 through 1970 for the specified vehicle components.

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
1967-1970	257
1966	57
1963-1965	257
1962	57
1959-1961	257
1958	57

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon or BA9s base instrument bulb. 12V, 2W.	257
ANSI standard (US & Canada). Single-filament bulb with BA9s base. 12V, 1W.	57

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Additional Notes

The Austin Healey Sprite uses two bulb types for the license plate position across its 1958-1970 model years: the 257 and the 57, both of which are ANSI-standard bulbs rated for the US and Canadian markets.
The 257 bulb operates at 12 volts and draws 2 watts, while the 57 bulb operates at 12 volts but draws only 1 watt, making the two types distinct in power consumption despite sharing the same voltage rating.
Both the 257 and the 57 bulb use a BA9s base, which is a miniature bayonet-style cap with a 9mm collar width commonly found in small instrument and auxiliary lighting applications.
The 257 is described as a festoon or BA9s base instrument bulb, meaning it may be available in either a cylindrical festoon form or the BA9s cap configuration, depending on the specific unit sourced.
The 57 is a single-filament bulb, a construction type that contains one tungsten filament and serves a single lighting function, in this case license plate illumination.
The 257 bulb is specified for the Austin Healey Sprite across the majority of model years in the dataset, covering 1959-1965, 1967-1970, with the exception of 1963 and 1964 which also use the 257.
The 57 bulb appears in three non-consecutive model years: 1958, 1962, and 1966, indicating that the lower-wattage single-filament type was not the predominant fitment across the production run.
Although both bulbs share a BA9s base, the difference in wattage between the 257 and the 57 means the two types are not functionally interchangeable without accounting for the variation in light output.