Bulb Replacement Planner
Plan headlight, taillight, and interior bulb replacement before they fail. Different bulb technologies have very different service lives — knowing what you have helps you decide whether to replace individually or upgrade the whole pair to LED.
Battery Life Predictor
Predict remaining battery life from age, climate, driving pattern and technology.
How It Works
Bulb life depends on technology and duty cycle. Halogen bulbs degrade gradually — light output drops 20% by 70% of life. LED bulbs typically run 10–25× longer but fail differently (sudden, or partial color shift). HID bulbs have the shortest practical life of the modern options.
How to Use This Calculator
- Identify your bulb technology — halogen, HID/xenon, or LED.
- Enter the bulb’s rated life (printed on the box) and how long you’ve had it.
- Add estimated daily headlight-on hours (commute time × 2 if you drive at night).
- The calculator returns remaining life percent and replacement recommendation.
Worked Example
Reference Table
Typical bulb life by technology. Replace both bulbs of a pair simultaneously to keep brightness even — a single new bulb next to a worn one looks unbalanced on the road.
| Bulb type | Rated life | Real-world life | Replace as pair |
|---|---|---|---|
| Halogen H7/H11 | 500–1000 h | 8–24 months | Yes — uneven brightness |
| Halogen 9006/H4 | 400–700 h | 6–18 months | Yes |
| Long-life halogen | 1500–2000 h | 24–48 months | Recommended |
| HID/Xenon D2S/D2R | 2000–3000 h | 4–6 years | Yes — color shift visible |
| LED retrofit | 15 000–30 000 h | 10–15 years | Optional |
| LED OEM (sealed) | 30 000–50 000 h | 15–20 years | Whole assembly replaces |
| Tail/marker incandescent | 500–1500 h | 2–5 years | Optional |
Frequently Asked Questions
Should I upgrade halogen to LED?
Yes, but only with proper LED retrofits that match your headlight optics. Plug-and-play LEDs in halogen reflectors often produce glare for oncoming drivers. Projector headlights handle LEDs better than reflector headlights.
Why did my new halogen bulb die so fast?
Most common cause: touching the glass with bare fingers during install — skin oils create hot spots that crack the bulb. Always use gloves or hold the bulb by its plastic base.
Do bulb pairs really need to be replaced together?
For halogen and HID, yes — you can clearly see brightness and color difference when one bulb is new and the other is 80% through its life. For LED, less critical because LEDs don’t dim gradually.
How much does a headlight bulb cost?
Halogen H7/H11: $15–40 per pair. Long-life halogen: $25–60. HID D2S/D2R: $40–150 each. LED retrofits: $50–250 per pair. OEM LED assemblies: $400–1500 each.
Can I replace my own headlight bulb?
On most older cars, yes — 10 minutes per side. On modern cars (especially BMW, Audi, Tesla) you may need to remove the entire front bumper to access the bulb, which makes professional replacement worthwhile.
