2018 Kia Optima Headlight Bulb Size
The 2018 Kia Optima uses a 9005 low-beam headlight bulb.
Key takeaways
- Low beam: 9005.
- The 9005 low beam is halogen: a cheap bulb, sold everywhere, and usually a ten-minute job.
- Fog, signal, and reverse bulbs use different sizes - check each before buying.
- Fog light
- H8
- Front turn signal
- 1157
- Brake / tail
- 1157
- Rear turn signal
- 1156
- Reverse / backup
- 921
- License plate
- 168
SX / SX Turbo (and some EX/Limited) ship factory full-LED low+high beam projectors not user-replaceable; default positions describe halogen LX/EX/S trims. Bulb sizes can vary by trim and headlight type, so confirm against your existing bulb.
Where to buy bulbs for the 2018 Kia Optima
Headlight bulbs dim over time, so replace them in pairs even if only one has failed. Most are a 10-minute DIY job. 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: 9005 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 |
|---|---|---|---|
| 9005 | low beam | Halogen | a pair |
9005 is a widely used headlight bulb, fitted to 2.8% 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) | 9005 | Halogen |
| Fog light | H8 | Halogen |
| Front turn signal | 1157 | Miniature |
| Brake / tail | 1157 | Miniature |
| Rear turn signal | 1156 | Miniature |
| Reverse / backup | 921 | Miniature |
| License plate | 168 | Miniature |
SX / SX Turbo (and some EX/Limited) ship factory full-LED low+high beam projectors not user-replaceable; default positions describe halogen LX/EX/S trims.
Fourth-gen (JF). Halogen-trim low beam is 9005 (HB3). High beam left null: dual-projector halogen trims use H7 while single-projector trims use 9005 for both, not pinned to two agreeing sources. Fog H8.
Should you upgrade to LED?
The obvious question is whether you can drop an LED into a 9005 halogen housing. Physically, usually yes, and the kits are everywhere. Whether you should is a different matter, and it comes down to your housing. A projector housing has a lens and a cutoff shield that keeps light on the road, and a well-made LED in a projector is generally fine. A reflector housing aims light using the bowl geometry, which was designed around the exact position and shape of a halogen filament. An LED does not put light in the same place, so the reflector scatters it - you get more glare for oncoming traffic and often less usable light on the road, while your own view feels brighter because the source is whiter. Look at your housing before you buy: if you can see a lens, you have a projector. Note too that DOT-compliant LED replacements for halogen housings are rare, which is a legality issue in some states and an inspection issue in others.
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 2018 Kia Optima take?
It uses a 9005 low-beam bulb and a null high-beam bulb.
Is the 2018 Kia Optima headlight bulb a DIY job?
The 2018 Kia Optima uses 9005 halogen low beams, which is the straightforward case: a real bulb, available anywhere, usually a ten-minute job. The one rule that matters is not touching the glass with bare fingers. Skin oil creates a hot spot that will kill the bulb early - handle it by the base, and if you do touch it, wipe it with rubbing alcohol before fitting.
What fog light bulb does the Kia Optima use?
The fog lights take a H8 bulb.
Can I put LED bulbs in a 2018 Kia Optima?
The obvious question is whether you can drop an LED into a 9005 halogen housing. Physically, usually yes, and the kits are everywhere. Whether you should is a different matter, and it comes down to your housing. A projector housing has a lens and a cutoff shield that keeps light on the road, and a well-made LED in a projector is generally fine. A reflector housing aims light using the bowl geometry, which was designed around the exact position and shape of a halogen filament. An LED does not put light in the same place, so the reflector scatters it - you get more glare for oncoming traffic and often less usable light on the road, while your own view feels brighter because the source is whiter. Look at your housing before you buy: if you can see a lens, you have a projector. Note too that DOT-compliant LED replacements for halogen housings are rare, which is a legality issue in some states and an inspection issue in others.
Is 9005 a common headlight bulb?
9005 is a widely used headlight bulb, fitted to 2.8% 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.