Automotive LED bulb cross reference chart
Automotive LED Bulb Cross Reference Chart: 194, 7440, 7443, 3156, 3157, 921 & More
Choosing a replacement automotive LED bulb can be confusing because the same socket or bulb family may be sold under several different part numbers. A vehicle may call for a 194, 168, W5W, 7440, 7443, 3156, 3157, 921, DE3175, 578, or another number even when the bulbs look very similar.
This automotive LED bulb cross reference guide helps you identify common bulb families, understand which numbers are closely related, and avoid ordering a bulb that fits physically but does not match the electrical function of the original lamp.
Important: A cross-reference number does not always mean two bulbs are electrically identical. Before ordering, verify the socket shape, contact layout, single- or dual-circuit design, bulb dimensions, light function, and the bulb currently installed in your vehicle.
Quick Automotive LED Bulb Cross Reference Chart
| Bulb Family | Common Cross-Reference Numbers | Typical Automotive Uses |
|---|---|---|
| T10 / 194 / 168 | 194, 168, 158, 161, 192, 193, W5W, 2821, 2825, 2827, 579 | Map, dome, door, courtesy, trunk, cargo, license plate, side marker |
| 7440 / T20 | 7440, 7441, 992, 7440ST, 7440LL, 7440A | Reverse, turn signal, parking, tail applications depending on vehicle |
| 7443 / T20 | 7443, 7443ST, 7443LL, 7444NA | Brake/tail, turn signal, parking, reverse applications depending on vehicle |
| 3156 / T25 | 3156, 3156A, 3156AK, 3156ST, 3156LL, 3456, 3456LL | Reverse, turn signal, parking, tail applications depending on vehicle |
| 3157 / T25 | 3157, 3057, 3357, 3457, 4157, 3155, 4057 and related variants | Brake/tail, turn signal, parking, reverse applications depending on vehicle |
| 1156 / BA15S | 1156, 1141, 7506, 5008, 5007, 1155, 1073, 3497 | Reverse, turn signal, parking and single-circuit lamps |
| 1157 / BAY15D | 1157, 7528, 2057, 2357, 3496, 1034, 2397 | Brake/tail, turn signal and dual-circuit lamps |
| T15 / 921 / 912 | 921, 912, 920, 922, 906, 916, 917 | Reverse, cargo and high-mount stop lamp applications |
| 31mm Festoon | DE3175, DE3021, DE3022, 3175, 3022, 6428, 7065 | Dome, map, vanity, trunk and cargo lights |
| 36mm–37mm Festoon | 6418, 3910, 3423, 3425, 6411, 6423, 6461, 3710 | Dome, map, vanity, trunk and cargo lights |
| 41mm–42mm Festoon | 578, 211-2, 212-2, 214-2, 4210, 6413, 6429, DE3423, DE3425 | Dome, map, door, courtesy, trunk and cargo lights |
T10, 194 and 168 LED Bulbs
The T10 wedge family is one of the most common automotive interior and small exterior bulb groups. Numbers such as 194, 168, W5W, 158, 192, 2821 and 2825 are frequently associated with the same general wedge-style socket family.
These bulbs are commonly used for map lights, dome lights, door courtesy lights, trunk or cargo lights, license plate lights and side marker lights. However, the original halogen bulbs may have different wattage or brightness ratings even when the base looks similar.
When converting to LED, verify the available space inside the housing because some high-output LED replacements are wider or longer than the original halogen bulb.
7440 vs. 7443: What Is the Difference?
7440 and 7443 are both T20-style wedge bulbs, but they are not electrically identical.
7440 is a single-circuit bulb. It is designed for one lighting function and uses one electrical circuit.
7443 is a dual-circuit bulb. It can support two lighting levels or functions in applications designed for a dual-circuit socket.
Because the contact arrangement and vehicle wiring matter, do not assume that a 7440 and 7443 are interchangeable in every application simply because the base dimensions are similar. Match the bulb to the original socket and the function used by your vehicle.
If your vehicle uses this bulb family for reverse or other compatible applications, see the SAWE 7443 / 7440 / 7444 T20 LED bulb. You can also browse the SAWE LED reverse light collection for additional bulb sizes.
3156 vs. 3157: Single Circuit vs. Dual Circuit
The 3156 and 3157 bulb family follows a similar pattern. A 3156 is generally associated with a single-circuit application, while a 3157 is commonly used in dual-circuit applications such as brake/tail or parking/turn combinations.
Related 3157-family numbers include 3057, 3357, 3457, 4057 and 4157 variants. Related 3156-family numbers include 3156, 3456 and several long-life or amber versions.
Physical fit alone does not guarantee correct operation. Always check the socket contacts and the original bulb number before replacing a 3156 or 3157.
For compatible applications, view the SAWE 3156 / 3157 / 4157 T25 LED bulb.
1156 vs. 1157 LED Bulbs
The 1156 and 1157 bulb families use metal bayonet bases, but their electrical layouts differ.
1156 / BA15S is generally a single-circuit bulb. Common related numbers include 1141, 7506, 5008, 5007, 1155, 1073 and 3497.
1157 / BAY15D is generally a dual-circuit bulb. Related numbers include 7528, 2057, 2357, 3496, 1034 and 2397.
For compatible dual-circuit applications, see the SAWE 1157 BAY15D LED bulb.
921, 912 and T15 LED Bulbs
T15 bulbs are commonly used for reverse lights and cargo lighting. The 921 and 912 are two of the best-known numbers in this family, with related references including 906, 916, 917, 920 and 922.
T15 should not be confused with the smaller T10 / 194 / 168 wedge family. Although both use wedge-style bases, a T15 bulb is physically larger and is normally used in higher-output applications.
For a bright 6000K white reverse-light option, see the SAWE 921 / 912 T15 projector LED reverse light bulb.
Festoon LED Bulb Sizes: 31mm, 36mm and 41mm
Festoon bulbs are different from wedge and bayonet bulbs because the electrical contacts are located at both ends of the bulb. The most important factor is usually the overall bulb length.
31mm Festoon
Common 31mm references include DE3175, DE3021, DE3022, 3175, 3022 and 6428. These bulbs are frequently used for dome, map, courtesy, trunk and cargo lighting.
See the SAWE 31mm DE3175 festoon LED bulbs.
36mm–37mm Festoon
Common references include 6418, 3910, 3423, 3425, 6411, 6423, 6461 and 3710. Measure the original bulb before ordering because even a few millimeters can affect how securely a festoon bulb fits between the spring contacts.
41mm–42mm Festoon
Common references include 578, 211-2, 212-2, 214-2, 4210, 6413 and 6429. These larger festoon bulbs are commonly found in dome, map, door courtesy, trunk and cargo light housings.
See the SAWE 578 / 211-2 / 212-2 41mm–42mm LED bulb.
Headlight and Fog Light Cross References
| Bulb | Common Reference | Important Note |
|---|---|---|
| 9005 | HB3 | Common high-beam and daytime-running-light bulb family |
| 9006 | HB4 | Common low-beam and fog-light bulb family |
| H3 | H3-55W, H3-35W | Verify wattage and housing type |
| H8 / H11 | Closely related families | Do not assume interchangeability without checking the socket tabs and vehicle application |
What Does the “A” Mean in a Bulb Number?
When a bulb number ends in A, such as 1157A or 7440A, the “A” typically identifies an amber version. If the vehicle uses a clear lens for a turn signal or marker light, make sure the replacement LED produces the correct legal light color for that position.
How to Choose the Correct LED Replacement Bulb
- Check the original bulb number. Remove the factory bulb and read the number printed on the base or glass whenever possible.
- Match the socket and contacts. Verify wedge, bayonet or festoon style and confirm the number of electrical contacts.
- Confirm single- or dual-circuit operation. This is especially important with 7440/7443, 3156/3157 and 1156/1157 families.
- Measure the available space. LED replacements can be longer or wider than the original halogen bulb.
- Match the light color to the application. For example, an amber turn signal behind a clear lens should use an amber LED.
- Check for vehicle-specific electronic requirements. Some vehicles may need CANBUS-compatible LEDs or additional load resistance for turn-signal applications.
Vehicle Bulb Size Can Vary by Year and Trim
Even when two vehicles share the same model name, bulb sizes can change by model year, trim level, factory lighting package or body style. A cross-reference chart should therefore be used as a starting point rather than the only fitment check.
For vehicle-specific examples, see the Toyota Corolla bulb size guide or the Honda Accord bulb size guide.
Frequently Asked Questions
Are 194 and 168 bulbs interchangeable?
194 and 168 bulbs belong to the same common T10-style wedge family and often fit the same socket. Original halogen specifications such as wattage and brightness can differ, so check the vehicle application before choosing a replacement.
Is a 921 bulb the same as a 194 bulb?
No. A 921 is generally a larger T15 wedge bulb, while 194 and 168 are commonly associated with the smaller T10 wedge family. They should not be treated as the same bulb size.
Can I replace a 7440 with a 7443?
Do not rely on the bulb number alone. A 7440 is a single-circuit design, while a 7443 is a dual-circuit design. Some sockets may be physically related, but correct operation depends on the contact layout and the vehicle's electrical function.
Can I replace a 3156 with a 3157?
3156 and 3157 are closely related T25 bulb families, but they are designed for different circuit configurations. Verify the socket contacts and the original bulb function before making the substitution.
How do I know which festoon size I need?
Measure the original festoon bulb from end cap to end cap. Common automotive sizes include approximately 31mm, 36mm–37mm and 41mm–42mm.
Why does an LED turn signal hyperflash?
LED bulbs draw less current than traditional incandescent bulbs. Some vehicles interpret the lower electrical load as a failed bulb, which can cause fast flashing or a dashboard warning. Depending on the vehicle, a compatible LED solution, resistor or electronic flasher may be required.
Shop Automotive LED Bulbs by Size
Once you have confirmed the correct bulb family and application, browse SAWE Lighting LED replacements for reverse lights, interior lights, dome lights, map lights, trunk lights, cargo lights and other automotive lighting positions.
- 7440 / 7443 / 7444 T20 LED Bulbs
- 3156 / 3157 / 4157 T25 LED Bulbs
- 921 / 912 T15 LED Reverse Bulbs
- 1157 BAY15D LED Bulbs
- 31mm DE3175 Festoon LED Bulbs
- 578 / 211-2 / 212-2 41mm–42mm LED Bulbs
- All SAWE LED Reverse Light Bulbs
Final fitment reminder: Automotive lighting can vary by year, trim and factory equipment. Always verify the original bulb number and socket configuration before ordering.
