CR2032 — the everyday 20 × 3.2 mm lithium
Very common on smart-entry remotes and many integrated keyheads. About 20 mm across and 3.2 mm thick.
Not a drop-in for thinner 20 mm cells (CR2025 / CR2016) or larger 24 mm cells (CR2450).
CR2025 — thinner 20 mm (sometimes two)
Same diameter family as CR2032 but about 2.5 mm thick. Some older Ford Intelligent Access keys use two CR2025 — quantity matters as much as the code.
Do not stack random cells to “make thickness.” Use the quantity the manual names.
CR2450 — larger 24 × 5.0 mm
Common on later Ford IA / push-button keys and some Toyota smart keys (for example later Corolla). Physically larger than CR2032 — it will not seat in a CR2032 tray.
Never substitute CR2032 “because it’s close” or CR2450 into a CR2032 fob.
CR1620 and CR2016 — smaller remotes
CR1620 (~16 × 2.0 mm) appears on many Honda Master / screw-cover remotes.
CR2016 (~20 × 1.6 mm) appears on older Toyota non-smart remotes. Same width family as CR2032 does not make it a swap.
Quantity and polarity
Read “one” vs “two” on the answer plate. Two CR2025 is not one CR2450.
Follow the tray or figure polarity. After a correct fresh cell still fails, see polarity and contacts and the safe key-fob replacement guide — not a second wrong code.
Quick takeaway
Code + quantity from the model-year key-type answer. Size letters alone are not enough.