2021 Mercedes-Benz C-Class Headlight Bulb Size
The 2021 Mercedes-Benz C-Class comes with factory LED headlights (not bulb-replaceable) on equipped trims. Halogen trims use a H7 fog light bulb.
Key takeaways
- Low beam: LED. High beam: LED.
- This trim has factory LED headlights, which are often sealed into the assembly - check yours comes out before buying anything.
- Fog, signal, and reverse bulbs use different sizes - check each before buying.
- Fog light
- H7
- Front turn signal
- LED
- Brake / tail
- LED
- Rear turn signal
- LED
- Reverse / backup
- LED
- License plate
- W5W
Headlights for the 2021 Mercedes-Benz C-Class
This vehicle uses factory LED headlights on equipped trims. If one fails, the part is a headlight assembly, not a bulb, so it is usually a dealer or body-shop job rather than a DIY swap.
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Can you replace it yourself?
Every bulb on this vehicle
Headlights get the attention, but the small bulbs are what fail an inspection. A burnt-out brake or turn bulb is also the cheapest ticket you will ever get, and most of these are a few dollars and a twist to change.
| Position | Bulb | Type |
|---|---|---|
| Low beam (headlight) | LED | LED |
| High beam | LED | LED |
| Fog light | H7 | Halogen |
| Front turn signal | LED | LED |
| Brake / tail | LED | LED |
| Rear turn signal | LED | LED |
| Reverse / backup | LED | LED |
| License plate | W5W | Miniature |
W205; base trim uses halogen H7 low/high with H7 fog; Sport/AMG has LED headlights standard in US. Fog light H7 applies to halogen trims only.
Why this keeps getting harder
Headlight bulbs used to be a commodity: a handful of codes covered most cars and any of them cost a few dollars. That is ending. Across the vehicles we hold specs for, factory LED low beams went from 0% of 2000s cars to 59% of 2025-and-newer ones. LEDs last far longer, which is the upside and a real one. The tradeoff is that when they do fail, it is often not a bulb you can buy at all, and the fix moves from a $20 part to a headlight assembly.
- The full LED adoption study - how fast the fleet switched, measured across our own data.
- Halogen vs LED vs HID - what actually differs, beyond the marketing.
- How to change a headlight bulb - the ten-minute version.
- The most common headlight bulb types
Frequently asked
What headlight bulb does a 2021 Mercedes-Benz C-Class take?
Equipped trims use factory LED headlights, which are sealed assemblies rather than replaceable bulbs.
Is the 2021 Mercedes-Benz C-Class headlight bulb a DIY job?
The 2021 Mercedes-Benz C-Class has factory LED low beams. Factory LED headlights are often sealed into the assembly rather than being a serviceable bulb, so before you buy anything, check whether yours actually comes out. If it does not, the failure is at the assembly level, and it is worth having the driver and connectors checked before replacing the whole unit, because that is usually where LED headlights actually fail.
What fog light bulb does the Mercedes-Benz C-Class use?
The fog lights take a H7 bulb.
See where this ranks in our study of the most common headlight bulb types in the US.