Ford F-250 Super Duty Back Up Light Bulb Size

The Ford F-250 Super Duty back up light utilizes bulb sizes WT21W, 7440, 3157, 921, 2356, 2456, and 3156. Available data for the specified components covers the range from 1999 to 2023.

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
2021-2023	WT21W
2020	7440 (With Halogen Capsule Headlamps)
2019	3157
2017-2018	7440
2011-2016	921
2010	2356
2009	921
2004-2008	2456
2003	3156
2002	2456
2001	2356
2000	2456
1999	3156

Bulb Specifications

Description	Bulb Size
Ford OEM part. Single-filament wedge bulb (T20). Originally used in 2021+ Ford F-150, Bronco, and Maverick. 12V, 21W.	WT21W
ANSI standard (US & Canada). Single-filament wedge bulb (T20). 12V, 21W.	7440
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V.	2356
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3156

Other Locations

Additional Notes

The Ford F-250 Super Duty backup light specifications span model years 1999 through 2023, with seven distinct bulb sizes used across that range: WT21W, 7440, 3157, 921, 2356, 2456, and 3156.
The 921 is the most frequently specified bulb in this application, covering the 2011-2016 model years as well as 2009. It is a T15 wedge bulb rated at 12V and 16W under the ANSI standard.
The 2456 is the second most common bulb in the specifications, appearing in the 2000 and 2002 model years as well as the 2004-2008 range. It is an ANSI-standard festoon bulb rated at 12V for specialty applications.
The WT21W covers the 2021-2023 model years. It is a Ford OEM part rather than an ANSI-standard bulb, sharing its T20 wedge form factor and 12V, 21W rating with the 7440 but originating as a fitment for the 2021 and later F-150, Bronco, and Maverick.
The 7440 is specified for the 2017-2018 model years and also for the 2020 model year when equipped with halogen capsule headlamps. Like the WT21W, it is a single-filament T20 wedge bulb rated at 12V and 21W, though it follows the ANSI standard.
The 2020 model year carries a conditional fitment note, with the 7440 applying specifically to trucks equipped with halogen capsule headlamps, indicating that backup light bulb selection on that year is dependent on headlamp configuration.
The 3157, specified for 2019, is a dual-filament T25 wedge bulb rated at 12V with a 27W primary filament and a 7W secondary filament. Its dual-filament design distinguishes it from the single-filament 3156, which shares the same T25 wedge base and 27W rating but was used in 1999 and 2003.
The 2356, used in 2001 and 2010, differs structurally from the other bulbs in the specifications. It uses a BAY15d bayonet base rather than a wedge or festoon mount, and it is a dual-filament design rated at 12V.
The WT21W and 7440 share identical physical and electrical characteristics as T20 single-filament wedge bulbs at 12V and 21W, but the WT21W is an OEM Ford part number rather than an ANSI-designated type, which is a relevant distinction for sourcing and cross-referencing purposes.
The base type varies considerably across the full specification range. Wedge bases appear in the T15, T20, and T25 form factors; a BAY15d bayonet base is used with the 2356; and a festoon mount is associated with the 2456, reflecting significant variation in socket design across model years.