2021 Lexus IS Headlight Bulb Size
The 2021 Lexus IS uses a D4S low-beam and a LED high-beam headlight bulb.
Key takeaways
- Low beam: D4S. High beam: LED.
- The D4S low beam is HID (xenon), not halogen - it runs through a ballast at high voltage, so it is a replaceable bulb but not a casual swap.
- Fog, signal, and reverse bulbs use different sizes - check each before buying.
- Fog light
- H11
- Front turn signal
- 7444NA
- Brake / tail
- 7443
- Rear turn signal
- 7440NA
- Reverse / backup
- 921
- License plate
- LED
Where to buy bulbs for the 2021 Lexus IS
Headlight bulbs dim over time, so replace them in pairs even if only one has failed. HID bulbs run through a ballast at high voltage, so this is a replaceable bulb but not a casual swap - disconnect the battery first. To order the exact sizes online:
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Can you replace it yourself?
What to buy
This vehicle uses separate bulbs for low and high beam: D4S for the low beam. They are different parts, so check which one has actually failed before buying. Replace them in pairs regardless. Bulbs from the same batch age at the same rate, so when one goes the other is usually close behind, and a fresh bulb beside a tired one is visibly brighter and unevenly aimed. Doing both at once costs a few dollars more and saves doing the job twice.
| Bulb | Covers | Type | Buy |
|---|---|---|---|
| D4S | low beam | HID | a pair |
D4S is a widely used headlight bulb, fitted to 1.8% of the vehicles we hold specs for. Any parts store will have it, and you are not restricted to the dealer.
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) | D4S | HID |
| High beam | LED | LED |
| Fog light | H11 | Halogen |
| Front turn signal | 7444NA | Miniature |
| Brake / tail | 7443 | Miniature |
| Rear turn signal | 7440NA | Miniature |
| Reverse / backup | 921 | Miniature |
| License plate | LED | LED |
Gen-3 IS (2014+) has D4S HID standard for low beam across all US trims; high beam is integrated LED. Fog is H11 on non-F-Sport; F-Sport fog may differ.
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 Lexus IS take?
It uses a D4S low-beam bulb and a LED high-beam bulb.
Is the 2021 Lexus IS headlight bulb a DIY job?
The 2021 Lexus IS uses D4S HID (xenon) low beams. This is a real bulb you can replace, but it is not a casual swap: HID runs through a ballast at several thousand volts to strike the arc, so disconnect the battery first and never handle a live system. Replace them in pairs - xenon bulbs shift colour as they age, and a new one next to an old one is obvious. Do not touch the glass with bare fingers.
What fog light bulb does the Lexus IS use?
The fog lights take a H11 bulb.
Is D4S a common headlight bulb?
D4S is a widely used headlight bulb, fitted to 1.8% of the vehicles we hold specs for. Any parts store will have it, and you are not restricted to the dealer.
See where this ranks in our study of the most common headlight bulb types in the US.