ANTHROPIC_DEFAULT_HAIKU_MODEL

Updated October 13, 2026 by Alex Sorokoletov

ANTHROPIC_DEFAULT_HAIKU_MODEL is a Claude Code environment variable: Override Haiku model ID. Its release history is not tracked here. It is listed in the official reference.

Status	Present in v2.1.294
Category	Models and thinking
Official docs	Listed

How to set it

For one session, export it in the shell that starts Claude Code:

export ANTHROPIC_DEFAULT_HAIKU_MODEL=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "<value>"
  }
}

Related variables

Frequently asked questions

What does ANTHROPIC_DEFAULT_HAIKU_MODEL do?

Override Haiku model ID

Which Claude Code version has ANTHROPIC_DEFAULT_HAIKU_MODEL?

Its release history is not tracked here.

How do I set ANTHROPIC_DEFAULT_HAIKU_MODEL?

Export it before starting Claude Code (export ANTHROPIC_DEFAULT_HAIKU_MODEL=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.