Most car key fobs use a small 3V coin cell battery, but the exact battery size is not universal. Even within the same brand, the battery size can change by model year and key style.
This car battery size guide focuses on key fob batteries, not the main car battery. Use it to quickly figure out what size battery goes in a key fob, then confirm the code on your current battery before you buy.
Common Key Fob Battery Sizes
The most common car key fob battery size options you will see are:
- CR2032
- CR2025
- CR1620
- CR1632
- CR2016
Tip: The fastest way to confirm the correct battery is to open the fob and read the code printed on the battery itself.
What Size Battery Goes in a Key Fob
If you are asking what size battery goes in a key fob, there are three reliable ways to check. Start with the quickest one.
Check 1 – Open the key fob and read the battery code
Open the key fob carefully and look at the top of the coin cell. You should see a code like CR2032 or CR2025. That printed code is what you buy.
If the battery code is worn off, use a flashlight and look at the side of the battery, or take a clear photo and zoom in.
Check 2 – Confirm key style and year
Key fobs come in different housings:
- Flip key
- Smart key
- Proximity key
The key style is important because two different key styles for the same car can use different batteries.
Check 3 – Use brand, model, and year as a starting point
If you cannot open the fob immediately, you can use brand and model as a starting guess. Then verify once you open the fob.
Key Fob Battery Size By Brand – Quick Reference Table
This table is a starting point. Always confirm your actual battery code before buying.
| Brand / keyword cluster | Most common key fob battery sizes (starting point) | What to verify before buying | Notes |
|---|---|---|---|
| Nissan – battery size for nissan key fob, nissan key battery size | CR2032, CR2025 | Year and key style (smart vs flip) | Nissan key fob batteries vary a lot by year |
| Lexus – battery size for lexus key fob | CR2032, CR2016, CR2025 | Smart key vs standard remote | Lexus keys can differ by trim and region |
| VW – battery size for vw key fob | CR2032, CR2025 | Flip key vs proximity key | VW key housings are not always consistent |
| BMW – bmw key battery size, what size battery for bmw key fob | CR2032, CR2025, CR2450 | Key generation and housing | Always confirm on-battery code |
| Honda – honda civic car key battery size, honda car key battery size | CR2032, CR2025, CR1616 | Year is critical | Honda changes battery sizes across generations |
| Jeep – what size battery for jeep key fob, jeep key battery size | CR2032, CR2025 | Exact fob design | Jeep has several fob designs for the same model |
| Audi Q7 – q7 key battery replacement | CR2032, CR2025 | Generation and key type | Confirm printed code on your battery |
What Size Battery Does a Car Key Fob Take – Common Questions
If you searched what size battery does a car key fob take, it usually comes down to two popular sizes:
- CR2032 is the most common overall
- CR2025 is also very common, slightly thinner than CR2032
Do not swap CR2025 and CR2032 unless your fob specifically supports both. They are close, but not identical in thickness.
Why Your Key Fob Battery Size Might Not Match What You See Online
If online answers do not match what you find in your key, these are the usual reasons:
- Your fob is a different style (flip key vs proximity key)
- Your car year is the same model but a different generation
- A previous owner replaced the shell with a different housing
- The key is for a different market or trim
If you want the highest accuracy, the battery code printed on the coin cell wins every time.
Vehicle Key Battery Empty – What It Usually Means
A vehicle key battery empty message typically means the key fob battery voltage is dropping under load. You may still be able to unlock and start the car for a while, but the range gets shorter and the warning becomes more frequent.
If you see this warning:
- Replace the key fob battery soon
- Replace it with a quality 3V coin cell
- Avoid touching the flat sides of the battery with your fingers
How Long Do Key Fob Batteries Last
Key fob battery lifespan depends on usage and how the fob is stored. In normal use, many key fob batteries last 1 to 3 years.
Battery life can drop faster if:
- The key is stored too close to the car (constant wake-ups)
- The car uses proximity entry and the key is always nearby
- Extreme heat or cold is common
- The battery is a low quality brand or old stock
Car Key Battery Lifespan Tips That Actually Help
To make a key fob battery last longer:
- Store the key away from the vehicle when possible
- Do not leave the key in the car
- Avoid cheap no-name coin cells
- Replace both batteries if your fob uses two
What To Do If You Still Cannot Find Your Key Fob Battery Size
If you still do not know what size battery for car key fob you need:
- Open the key and check the printed code
- If the code is unreadable, take a photo and zoom in
- Use the brand table above to get a starting point, then confirm
If you tell me your car brand, model, year, and whether your key is a flip key or smart/proximity key, I can format a tight lookup line for your page.
