I have a series 4 at 73%. That seems about right.

Update to 10.1.1. I heard this update resolves some of the battery drain issues some are having updaint to 10.1

Mine is 79%; 10 really drained battery but 10.1.1 is a little better

Get your battery replaced, it makes a big difference

I used to have battery drain issues with watchOS 10 on my s5. Like I would still comfortably make it through a day, but I noticed I had a lot less battery in the evening. The newest update fixed it tho, battery is back to how it was on watchOS 9.

Contact apple to service your battery. They will have you send it in and replace the whole watch for the cost of the battery as long as there are no cracks. It would be $99.