Can I use this battery instead?

Each code is looked up in the cross-reference (the same index as the finder on the battery hub), which gives the cell type and the size's datasheet diameter, height and voltage. The rules are tried in this order; the first that applies gives the verdict.

1. 1Same cell Both codes name the same cell (same size, same cell type): it is one battery sold under different names.
2. 2Never A primary cell (SR, LR, CR) never goes where the watch holds a rechargeable one (MT, CTL, TS…): a solar or kinetic watch charges its cell, and a primary cell is not made to be charged.
3. 3No A rechargeable cell does not replace a primary battery: a battery-powered watch has nothing to charge it with.
4. 4No Rechargeable cells of different systems (MT manganese-titanium, CTL cobalt-titanium) do not stand in for each other: the voltages differ.
5. 5No A different nominal voltage is a no: a 3 V lithium cell in a 1.55 V watch, or the reverse.
6. 6No A different diameter is a no: the cell does not sit in the holder.
7. 7No The same diameter with another height is a no: a taller cell stops the case back closing, a thinner one loses contact.
8. 8Fits, with a catch An alkaline LR cell fits where the silver oxide SR cell of the same size goes, but runs shorter; use it only to get the watch going.
9. 9Yes A silver oxide SR cell may replace an alkaline LR cell of the same size.
10. 10Fits, with a catch W (high drain) and SW (low drain) are the same size and voltage; use the type the watch maker names. High-drain cells are meant for watches with lights, alarms or chronographs.
11. 11Yes The same size and the same chemistry under another designation is a yes.

Heights within 0.05 mm count as the same: the datasheets round to that. A size without datasheet numbers in our sources gets “not sure” rather than a guess.