Pick the right Claude model in Claude Code

Claude Code lets you switch models per session with /model. Pick by capability, not a benchmark: reasoning-heavy work, routine coding, or cheap and fast. Costs and limits differ per model and plan, so match the model to the job.

1. Switch models with /model

/model

Run it with no argument to open the picker, where Enter sets the model as your default and s switches for this session only.

/model sonnet

Pass an alias or full name to switch immediately.

2. Match the model to the task

opus      # complex reasoning and architecture
sonnet    # daily coding tasks
haiku     # simple, fast tasks
opusplan  # Opus to plan, Sonnet to execute

Reach for Opus when a wrong decision is expensive, stay on Sonnet for routine work, and drop to Haiku for mechanical edits.

3. Set a default model

{
  "model": "sonnet"
}

Set the model key in settings to make it your default; /model writes this field for you. See pick an AI model for choosing a model across tools.

4. Weigh the cost and limit tradeoff

/usage

Opus draws down your allowance faster than Sonnet, and a model-specific limit stops only that family. Check what you have left, then see usage limits and track costs. Prices change, so check the current pricing page rather than trusting a number.

5. Pin a model id or alias

/model claude-opus-5-5

Pin an exact version by full id. If you are unsure of the id, open the picker or see the official models page; the same alias resolves to different versions on other providers.

Verify it worked

Run /model with no argument and confirm the model you expect is marked current.

If it fails:

• An alias reports an unknown model — your Claude Code is too old for that model; run claude update.
• The default keeps reverting — --model and ANTHROPIC_MODEL apply per session only; set the model key in settings instead.
• A subagent still runs Opus — subagents inherit the session model; set model: haiku in the subagent config.