Anthropic Shows Output Tokens Cost 5x Input in Claude Code

Anthropic published a breakdown of what actually drives a Claude Code session's token bill, per an August 14 post on its blog. The headline numbers: output tokens cost about five times input tokens. Decoding runs one token at a time, so it can't parallelize like reading a prompt does. Cache reads run at a tenth of the input price.

The catch is timing. On subscription plans, Anthropic says the prompt cache expires after one hour of inactivity. On API keys, it expires after five minutes. For subscription users running long agent sessions, that one-hour window sets the pace, not the model or the task list.

The post's guidance follows from the same math. Run /clear between unrelated tasks so you're not paying to reload a bloated context. Fix the model and effort level at the start of a session. Switching mid-conversation breaks the cache you already paid to build. @-mention a file directly instead of asking Claude Code to find it, which skips a Read call. Route noisy command output to a subagent, or add a quiet flag. Run /context in a fresh session to see which tool definitions are burning tokens unused. That routing advice lines up with a separate update that turned subagent forking on by default in Claude Code 2.1.232, per related coverage.

The take

Anthropic is describing cache management as a workflow discipline, not a background optimization Claude Code handles for you. That's a real change for subscription users who leave sessions open and assume the cost sorts itself out.