Why are my API calls higher than my messages sent?

Because some things the app does for you also run on your key without being a message you typed: translating a companion’s greeting, suggesting chat starters, summarising a long conversation, recovering a reply that never arrived, and reading a reply aloud. All of those are API calls, so they count towards your daily limit even though they are not messages you sent. Models, then Model API history, shows exactly which ones.