Apple watch battery drainage

Yesterday, I received a new Apple Watch Series 4, the first time I have owned an Apple Watch. I updated it to the latest Watch OS, fooled around with it a bit, then put it down to charge. I charged it to 100%. About 12 hours later, it was down to 88%, and I hadn't touched it. About 12 hours after that, it was down to about 77%, again after not having touched it. Is this normal?