Claude Code: how to change the model with /model or --model

Claude Code how to change model: type /model during a session and pick one, or start Claude Code with claude --model <name>. Both are documented in the Claude Code model configuration docs, which also cover the environment variable and settings file routes. Which one wins depends on where you set it, and that is where most people get stuck.

This guide is for anyone who uses Claude Code in a terminal and wants to switch between models like Opus, Sonnet and Haiku, or make a choice stick. The details below were read from the official docs on October 29, 2026. Model names and defaults change, so check the docs if something here looks off. If you haven't set Claude Code up yet, start with how to install it.

The five ways to set the model

The docs list them from highest priority to lowest:

ANTHROPIC_DEFAULT_MODEL needs Claude Code v2.1.236 or later.

How to change the model during a session

Run /model with no argument to open the picker, or give it a name:

/model sonnet

In the picker, Enter switches and saves the choice as your default for new sessions, by writing the model field in your user settings. Press s instead to switch for this session only.

You can also switch without clearing what you've typed. The interactive mode docs list Option+P on macOS and Alt+P on Windows and Linux for this. On macOS, your terminal must treat Option as Meta for that shortcut to work.

One cost to know about: each model has its own prompt cache, so the first request after a switch re-reads the whole conversation without the cache, according to the settings docs.

How to start Claude Code on a specific model

Use the --model flag. It takes an alias or a full model name, and it overrides both the model setting and ANTHROPIC_MODEL:

claude --model opus

To pin an exact version, use the full name, such as claude --model claude-sonnet-5. The flag applies only to the session you start with it.

How to set a default model

For a default that survives restarts, use one of these.

Settings file. Add a model field to a settings file:

{
  "model": "opus"
}

The file you pick sets who it applies to:

The docs give an example of the local file at work. If your team's shared file sets one model and you want another, put yours in .claude/settings.local.json and only your sessions change.

Environment variable. Export it before launching:

export ANTHROPIC_MODEL=opus
claude

ANTHROPIC_MODEL beats the model key in any settings file. ANTHROPIC_DEFAULT_MODEL does the opposite: it applies only when no file sets model.

One session without saving. Pass settings inline:

claude --settings '{"model": "claude-opus-5-5"}'

Model aliases you can use

As of October 29, 2026, the docs list these aliases:

On the Anthropic API, opus maps to Opus 5.5, sonnet to Sonnet 5.5 and haiku to Haiku 5.5. On Amazon Bedrock and Google Cloud's Agent Platform, sonnet maps to Sonnet 4.5 and haiku to Haiku 4.5. On Microsoft Foundry, opus maps to Opus 4.6. To change what an alias points to, set ANTHROPIC_DEFAULT_OPUS_MODEL, ANTHROPIC_DEFAULT_SONNET_MODEL or ANTHROPIC_DEFAULT_HAIKU_MODEL.

The docs say Fable is not the default on any plan. Pick it with /model fable or claude --model fable. Its usage may bill to usage credits, and interactive sessions show a consent prompt first.

Change the effort level too

Effort is separate from the model. Set it with /effort, claude --effort <level> or the CLAUDE_CODE_EFFORT_LEVEL variable. Levels run from low to max, depending on the model. According to the docs, the default is high on most models and medium on Opus 5.5, Sonnet 5.5 and Haiku 5.5. Run /effort auto to clear a level you saved.

Why your model keeps changing back

If a new session starts on a model you didn't pick, check these, all from the docs:

• A project or managed setting is overriding your /model choice. Project and managed settings reapply on each launch.
• ANTHROPIC_MODEL is exported in your shell and beats the settings file.
• Your organization restricts models with availableModels. A blocked choice is rejected in /model, or replaced at startup with a warning.
• You pressed s in the picker, so the choice was for one session only.
• Your user settings file is read-only, so /model could not save. The change applies now and is gone next session.

Run /status to see which settings files loaded, and claude doctor to list entries Claude Code rejected.

Where to go next

If you are comparing tools before you commit to one, see Claude Code vs Codex. For what usage costs, see Is Claude Code free.