Available models
For the model setting in Claude Code, you can configure either:
- A model alias
- A model name
- Anthropic API: A full model name
- Bedrock: an inference profile ARN
- Foundry: a deployment name
- Vertex: a version name
Model aliases
Model aliases provide a convenient way to select model settings without
remembering exact version numbers:
| Model alias | Behavior |
|---|
default | Recommended model setting, depending on your account type |
sonnet | Uses the latest Sonnet model (currently Sonnet 4.6) for daily coding tasks |
opus | Uses the latest Opus model (currently Opus 4.6) for complex reasoning tasks |
haiku | Uses the fast and efficient Haiku model for simple tasks |
sonnet[1m] | Uses Sonnet with a 1 million token context window for long sessions |
opusplan | Special mode that uses opus during plan mode, then switches to sonnet for execution |
claude-opus-4-6) or set the corresponding environment variable like ANTHROPIC_DEFAULT_OPUS_MODEL.
Setting your model
You can configure your model in several ways, listed in order of priority:
- During session - Use
/model <alias|name> to switch models mid-session
- At startup - Launch with
claude --model <alias|name>
- Environment variable - Set
ANTHROPIC_MODEL=<alias|name>
- Settings - Configure permanently in your settings file using the
model
field.
Example usage:
# Start with Opus
claude --model opus
# Switch to Sonnet during session
/model sonnet
{
"permissions": {
...
},
"model": "opus"
}
Restrict model selection
Enterprise administrators can use availableModels in managed or policy settings to restrict which models users can select.
When availableModels is set, users cannot switch to models not in the list via /model, --model flag, Config tool, or ANTHROPIC_MODEL environment variable.
{
"availableModels": ["sonnet", "haiku"]
}
Default model behavior
The Default option in the model picker is not affected by availableModels. It always remains available and represents the system’s runtime default based on the user’s subscription tier.
Even with availableModels: [], users can still use Claude Code with the Default model for their tier.
Control the model users run on
To fully control the model experience, use availableModels together with the model setting:
- availableModels: restricts what users can switch to
- model: sets the explicit model override, taking precedence over the Default
This example ensures all users run Sonnet 4.6 and can only choose between Sonnet and Haiku:
{
"model": "sonnet",
"availableModels": ["sonnet", "haiku"]
}
Merge behavior
When availableModels is set at multiple levels, such as user settings and project settings, arrays are merged and deduplicated. To enforce a strict allowlist, set availableModels in managed or policy settings which take highest priority.
Special model behavior
default model setting
The behavior of default depends on your account type:
- Max and Team Premium: defaults to Opus 4.6
- Pro and Team Standard: defaults to Sonnet 4.6
- Enterprise: Opus 4.6 is available but not the default
Claude Code may automatically fall back to Sonnet if you hit a usage threshold with Opus.
opusplan model setting
The opusplan model alias provides an automated hybrid approach:
- In plan mode - Uses
opus for complex reasoning and architecture
decisions
- In execution mode - Automatically switches to
sonnet for code generation
and implementation
This gives you the best of both worlds: Opus’s superior reasoning for planning,
and Sonnet’s efficiency for execution.
Adjust effort level
Effort levels control adaptive reasoning, which dynamically allocates thinking based on task complexity. Lower effort is faster and cheaper for straightforward tasks, while higher effort provides deeper reasoning for complex problems.
Three levels are available: low, medium, and high. Opus 4.6 defaults to medium effort for Max and Team subscribers.
Setting effort:
- In
/model: use left/right arrow keys to adjust the effort slider when selecting a model
- Environment variable: set
CLAUDE_CODE_EFFORT_LEVEL=low|medium|high
- Settings: set
effortLevel in your settings file
Effort is supported on Opus 4.6 and Sonnet 4.6. The effort slider appears in /model when a supported model is selected. The current effort level is also displayed next to the logo and spinner (for example, “with low effort”), so you can confirm which setting is active without opening /model.
To disable adaptive reasoning on Opus 4.6 and Sonnet 4.6 and revert to the previous fixed thinking budget, set CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING=1. When disabled, these models use the fixed budget controlled by MAX_THINKING_TOKENS. See environment variables.
Extended context
Opus 4.6 and Sonnet 4.6 support a 1 million token context window for long sessions with large codebases.
The 1M context window is currently in beta. Features, pricing, and availability may change.
- API and pay-as-you-go users: full access to 1M context
- Pro, Max, Teams, and Enterprise subscribers: available with extra usage enabled
To disable 1M context entirely, set CLAUDE_CODE_DISABLE_1M_CONTEXT=1. This removes 1M model variants from the model picker. See environment variables.
Selecting a 1M model does not immediately change billing. Your session uses standard rates until it exceeds 200K tokens of context. Beyond 200K tokens, requests are charged at long-context pricing with dedicated rate limits. For subscribers, tokens beyond 200K are billed as extra usage rather than through the subscription.
If your account supports 1M context, the option appears in the model picker (/model) in the latest versions of Claude Code. If you don’t see it, try restarting your session.
You can also use the [1m] suffix with model aliases or full model names:
# Use the sonnet[1m] alias
/model sonnet[1m]
# Or append [1m] to a full model name
/model claude-sonnet-4-6[1m]
Checking your current model
You can see which model you’re currently using in several ways:
- In status line (if configured)
- In
/status, which also displays your account information.
Environment variables
You can use the following environment variables, which must be full model
names (or equivalent for your API provider), to control the model names that the aliases map to.
| Environment variable | Description |
|---|
ANTHROPIC_DEFAULT_OPUS_MODEL | The model to use for opus, or for opusplan when Plan Mode is active. |
ANTHROPIC_DEFAULT_SONNET_MODEL | The model to use for sonnet, or for opusplan when Plan Mode is not active. |
ANTHROPIC_DEFAULT_HAIKU_MODEL | The model to use for haiku, or background functionality |
CLAUDE_CODE_SUBAGENT_MODEL | The model to use for subagents |
ANTHROPIC_SMALL_FAST_MODEL is deprecated in favor of
ANTHROPIC_DEFAULT_HAIKU_MODEL.
Pin models for third-party deployments
When deploying Claude Code through Bedrock, Vertex AI, or Foundry, pin model versions before rolling out to users.
Without pinning, Claude Code uses model aliases (sonnet, opus, haiku) that resolve to the latest version. When Anthropic releases a new model, users whose accounts don’t have the new version enabled will break silently.
Set all three model environment variables to specific version IDs as part of your initial setup. Skipping this step means a Claude Code update can break your users without any action on your part.
| Provider | Example |
|---|
| Bedrock | export ANTHROPIC_DEFAULT_OPUS_MODEL='us.anthropic.claude-opus-4-6-v1' |
| Vertex AI | export ANTHROPIC_DEFAULT_OPUS_MODEL='claude-opus-4-6' |
| Foundry | export ANTHROPIC_DEFAULT_OPUS_MODEL='claude-opus-4-6' |
ANTHROPIC_DEFAULT_SONNET_MODEL and ANTHROPIC_DEFAULT_HAIKU_MODEL. For current and legacy model IDs across all providers, see Models overview. To upgrade users to a new model version, update these environment variables and redeploy.
The settings.availableModels allowlist still applies when using third-party providers. Filtering matches on the model alias (opus, sonnet, haiku), not the provider-specific model ID.
Prompt caching configuration
Claude Code automatically uses prompt caching to optimize performance and reduce costs. You can disable prompt caching globally or for specific model tiers:
| Environment variable | Description |
|---|
DISABLE_PROMPT_CACHING | Set to 1 to disable prompt caching for all models (takes precedence over per-model settings) |
DISABLE_PROMPT_CACHING_HAIKU | Set to 1 to disable prompt caching for Haiku models only |
DISABLE_PROMPT_CACHING_SONNET | Set to 1 to disable prompt caching for Sonnet models only |
DISABLE_PROMPT_CACHING_OPUS | Set to 1 to disable prompt caching for Opus models only |
DISABLE_PROMPT_CACHING setting takes precedence over the model-specific settings, allowing you to quickly disable all caching when needed. The per-model settings are useful for selective control, such as when debugging specific models or working with cloud providers that may have different caching implementations.
