But basically you get ~300Mn input tokens and ~100Mn output tokens per month with Sonnet on the $100 plan. These are split across 50 sessions you are allowed, each session is 5 hrs starting from the first time you send a message until 5 hrs after the first message. During this time, you get ~6Mn input and ~2Mn output tokens for Sonnet. Claude Code seems to use a mix of Sonnet and Haiku, and Haiku has 2x the limits of Sonnet.

So if you absolutely maxed out your 50 sessions every month, that's $2400 worth of usage if you instead had used the API. So it's a great deal. It's not $100 worth of API credits you're buying, so they don't run out like that. You can exhaust limits for a given session, which is at most a 5 hr wait for your next one, or you can run out of 50 sessions, I don't know how strongly they enforce that limit and I think that limit is BS, but all in all the value for money is great, way better than using the API.