Mercury Capri Headlight Bulb Size

Mercury Capri high beam and low beam headlight bulbs utilize H4666, H4651, H5001, H4652, and H4656 bulb sizes across different model generations. The replacement chart covers 1970 to 1994 production years with corresponding bulb size specifications.

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

High Beam Headlight

Years	Bulb Type	Shop
1991-1994	H4666	Check Price
1979-1986	H4651	Check Price
1970-1977	H5001	Check Price

Low Beam Headlight

Years	Bulb Type	Shop
1991-1994	H4666	Check Price
1985-1986	H4652	Check Price
1983-1984	H4656	Check Price
1980-1982	H4652	Check Price
1979	H4656	Check Price
1970-1977	H5006	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4666	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4651	Check Price
ANSI standard (US & Canada). 4-inch square sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5001	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit, variant of H4651. Not a replaceable bulb — the entire unit is replaced. 12V.	H4652	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4656	Check Price
ANSI standard (US & Canada). 5.75-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5006	Check Price

Other Locations

Additional Notes

The Mercury Capri uses three distinct sealed beam form factors across its model years: a 4-inch square unit (H5001/H5006), a 4x6-inch rectangular unit (H4651/H4652/H4656), and a rectangular sealed beam unit without a published inch rating (H4666). All are ANSI-standardized for the US and Canadian markets and operate at 12V.
All bulb types listed for the Mercury Capri are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When a filament fails, the entire unit requires replacement rather than an internal bulb swap.
The H4666 is the sole bulb type used for both high and low beam positions on the 1991-1994 model years, indicating a single sealed beam unit serves dual functions in that application.
The H4651 and H4652 are both 4x6-inch rectangular sealed beam units sharing the same physical format, with H4652 classified as a variant of H4651. Despite this relationship, the two are not listed interchangeably across all years, as the low beam position on the 1979 and 1983-1984 model years uses H4656 rather than H4652.
The 1970-1977 model years use the H5001 for high beam and the H5006 for low beam. Both are round sealed beam units, with H5001 measuring 4 inches square and H5006 measuring 5.75 inches in round format, making them physically non-interchangeable despite serving the same vehicle generation.
The low beam position on the 1979 and 1983-1984 model years takes the H4656, while surrounding years in the same era use the H4652. Both are 4x6-inch rectangular sealed beam units, but they carry different ANSI designations and are not listed as interchangeable in these specifications.