Ducati Monster 821 Headlight Bulb Size

The Ducati Monster 821 headlight bulb sizes include H1 and H7 bulb types for high and low beam functions respectively. Replacement chart data spans from 2015 to 2020 model 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

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2019-2020	H1	H1	Check Price
2018	9003	H4	Check Price
2018	H1	H1	Check Price
2015-2017	9003	H4	Check Price

Low Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2019-2020	H7	H7	Check Price
2018	9003	H4	Check Price
2018	H7	H7	Check Price
2015-2017	9003	H4	Check Price

Bulb Specifications

Description	Type	Shop
ECE standard (Europe & worldwide). Single-filament halogen bulb with P14.5s base. Also approved in the US and Japan. 12V, 55W.	H1	Check Price
ANSI standard (US & Canada). Dual-filament halogen bulb with P43t base. 12V, 60W/55W.	9003	Check Price
ECE standard (Europe & worldwide). Single-filament halogen bulb with PX26d base. Also approved in the US and Japan. 12V, 55W.	H7	Check Price

Other Locations

Additional Notes

The H1 bulb is a single-filament halogen type operating at 55 watts with a P14.5s base. It is used exclusively for the high beam headlight on the Ducati Monster 821 for the 2019-2020 model years.
The H7 bulb is also a single-filament halogen type, rated at 55 watts, but uses a PX26d base. It serves the low beam headlight position on the 2019-2020 Monster 821, making it a distinct and non-interchangeable fitment from the H1 used in the high beam of those same years.
The 9003 bulb is a dual-filament halogen type that handles both high and low beam functions within a single housing. It is the specified bulb for both the high beam and low beam headlight positions on the 2015-2017 Monster 821.
The 2018 Monster 821 carries two separate entries for both the high beam and low beam positions, listing both the 9003 and the single-filament types (H1 for high beam, H7 for low beam). This reflects a mid-year or variant-based headlight assembly change within that model year.
Because the 9003 is a dual-filament bulb and the H1 and H7 are each single-filament bulbs with different base configurations, none of these three bulb types are interchangeable with one another despite serving the same vehicle positions across different years.
The transition from the dual-filament 9003 setup on the 2015-2017 Monster 821 to separate H1 and H7 single-filament bulbs on the 2019-2020 models indicates a change in headlight assembly design, where a single bulb unit was replaced by a two-bulb system with dedicated high and low beam elements.