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Quick answer
Short answer: use the battery your fob was built for. A CR2025 will work in a CR2032 fob to get you home, but it is 0.7 mm thinner and holds about a quarter less energy. Going the other way, a CR2032 is often too thick to let a CR2025 fob close. A CR2450 is a different size altogether and only fits fobs designed for it.
The numbers, from the makers' datasheets
| CR2025 | CR2032 | CR2450 | |
|---|---|---|---|
| Voltage | 3 V | 3 V | 3 V |
| Width | 20.0 mm | 20.0 mm | 24.5 mm |
| Thickness | 2.5 mm | 3.2 mm | 5.0 mm |
| Rated capacity | 165 mAh | 225 mAh | 620 mAh |
CR2025 and CR2032 figures are from Panasonic's datasheets. CR2450 is from Energizer's datasheet. Other brands rate their cells a little differently.
What happens when you swap
- CR2025 in a CR2032 fob: it fits and the voltage is the same, so the fob usually works. The thinner cell can sit loose and lose contact when the fob is bumped, and with 165 mAh instead of 225 mAh it runs down sooner. Fine as a stopgap; buy a CR2032 when you can.
- CR2032 in a CR2025 fob: the extra 0.7 mm can stop the case from snapping shut or press on the buttons. Don't force it, because the plastic clips crack easily.
- CR2450: 4.5 mm wider than the other two, so it won't fit a 20 mm slot and a 20 mm cell will rattle in a CR2450 slot. Jeep, for one, lists CR2450 as the replacement for the Wrangler fob.
New battery in and the fob still won't respond? See key fob not working after a battery change. Back to the key fob battery guide.
Questions people ask
Can I use a CR2025 in a key fob that calls for a CR2032?
It fits, since both are 20 mm wide and 3 volts, but it is 0.7 mm thinner and holds less (165 mAh vs 225 mAh in Panasonic's datasheets). It can sit loose and lose contact, and it will run out sooner. Use it to get home, then buy the right size.
Can I put a CR2032 in a fob made for a CR2025?
Usually not a good idea. The CR2032 is 0.7 mm thicker, so the case may not close fully or may press on the buttons. Forcing it can crack the clips that hold the case together.
Why do some key fobs use the bigger CR2450?
A CR2450 is 24.5 mm wide and 5.0 mm thick and Energizer rates it at 620 mAh, nearly three times a CR2032. Some carmakers use it in larger fobs. Jeep, for example, lists CR2450 as the replacement for the Wrangler fob. Only use it if your fob or manual calls for it.
Sources
Last checked Oct 23, 2026. WARNING: Lithium coin batteries are a severe ingestion hazard for children. Keep new and used cells locked away and check your vehicle owner's manual for exact fob specs.
