HOW TO DETERMINE SIZE OF MY APPLE WATCH
how to determine size of our 2 iwatches, i.e. size of case
Apple Watch Series 5, watchOS 8
Question marked as
If you have Apple Watch 5 as your signature suggests, they came in 40mm and 44mm sizes.
You can use a ruler to measure them.
You can open the watch app on your iPhone and go to General > About and note the model number and check the number in this link --> Identify your Apple Watch - Apple Support