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Choosing Headlight Bulb Sizes: H11 vs 9005, H7, H4 & More

How to find the right headlight bulb size for your vehicle — what H11, 9005, 9006, H7, H4, and 9012 mean, single vs. dual beam, and how to avoid buying the wrong bulb.

By Headlight Parts Team Updated July 22, 2026

The single most common mistake when upgrading headlights is buying the wrong bulb size. Headlight bulbs use standardized base codes — H11, 9005, 9006, H7, H4, 9012 and others — and they are not interchangeable. This guide, which applies to any car, truck, or SUV, helps you nail the right fitment before you buy. For parts, we point you to new bulbs and LED headlights on Amazon and OEM options on eBay Motors.

How to find your bulb size

  • Read the old bulb. The size code is usually molded into the plastic base — pull one and look.
  • Check the owner’s manual or the underhood label.
  • Use a fitment lookup by year, make, and model.

Many vehicles use one size for low beam and another for high beam, so always confirm both.

The common sizes, decoded

  • H11 — extremely common low-beam size. Single beam.
  • 9005 (HB3) — common high-beam size. Single beam. Often paired with H11.
  • 9006 (HB4) — common low-beam size on many vehicles. Single beam.
  • H7 — widespread single-beam size, especially on European vehicles.
  • H4 (9003/HB2) — a dual-beam bulb: low and high from one bulb per side.
  • 9012 (HIR2) — higher-output single-beam size on many newer vehicles.

Single beam vs. dual beam

This is the fitment detail people miss. A dual-beam bulb (like H4) has the low and high filament/LED in one bulb. A single-beam setup uses separate bulbs for low and high. Buying a single-beam bulb for a dual-beam socket (or vice versa) won’t work correctly — match this exactly.

A few buying tips

  • If you’re going LED, make sure the bulb is built for your housing type (reflector vs. projector) for a clean beam — see our LED vs HID guide.
  • Check whether your vehicle needs an anti-flicker harness with LED bulbs.
  • Buy in pairs and replace both sides at once so your beams match in color and brightness.

For used, OEM, and hard-to-find bulbs, use the eBay Motors buttons below; for new bulbs, follow the category links.

Shopping used or OEM? Try eBay Motors

Live listings for the parts covered in this guide — prices set by the seller.

Headlight bulbs (H11/9005/9006) H4 & H7 bulbs

Frequently Asked Questions

How do I find out what headlight bulb size my vehicle uses?
Check your owner's manual, the base of your existing bulb (the size is often molded into the plastic), or a bulb-fitment lookup by year/make/model. Many vehicles use one size for low beam and a different size for high beam, so verify both. When in doubt, pull the current bulb and read the code printed on it.
What's the difference between H11 and 9005?
They're different bulb bases with different tab shapes, and they are not interchangeable. H11 is a very common low-beam size; 9005 (HB3) is a common high-beam size. Many vehicles use H11 for low and 9005 for high — but always confirm your specific vehicle rather than assuming.
What does a dual-beam bulb like H4 or 9012 mean?
A dual-beam bulb (such as H4) produces both low and high beam from a single bulb, so one bulb per side handles everything. Single-beam setups use separate bulbs for low and high. 9012 (HIR2) is a higher-output single-beam size found on many newer vehicles. Matching single vs. dual beam correctly is essential for fitment.