Picking the wrong Claude model is expensive. Opus on every task costs 5x more than Sonnet for comparable results on most work. Haiku on a complex reasoning task produces worse output than just asking Sonnet. And if you are still using models from early 2025, some of them are deprecated — or will be soon. This guide covers every current Claude model, what each is good at, how much they cost, and a concrete decision framework for choosing the right one.

If you are calling the Claude API repeatedly with a large system prompt, a big document, or a long codebase context — and you are not using prompt caching — you are paying full price every time for content that has not changed. Prompt caching stores a prefix of your prompt server-side and charges 90% less to read it back on every subsequent request. For applications that repeatedly process the same context, this is the single highest-impact API optimisation available.

Token usage with Claude Code follows a frustrating pattern: costs are not spread evenly — they cluster around a handful of bad habits. Most developers using Claude Code daily are burning 40–60% more tokens than they need to, simply because of how they phrase prompts, what they put in CLAUDE.md, and which model they reach for by default. This guide covers five concrete changes that make an immediate difference. Why Tokens Are Worth Caring About Every message you send in a Claude Code session includes: