The Claude 4 Generation: All Three Models Explained

The Claude 4 Family

Claude 4 is Anthropic's current generation. The family has three tiers: Opus 4.7 (flagship reasoning), Opus 4.6 (mid-tier flagship), and Sonnet 4.6 (fast and affordable). All three are available in Claude Code and can be switched with a flag.

How They Differ

The primary differences are reasoning depth, cost, and speed. Opus 4.7 is the most capable and most expensive. Sonnet 4.6 is fast and cheap, sufficient for most development tasks. Opus 4.6 is in between — close to Opus 4.7 on most tasks, meaningfully cheaper.

Moving from Claude 3.x

If you are coming from Claude 3.5 Sonnet or Opus 3.5, the 4 generation is a significant upgrade in reasoning capability and tool use reliability. The API is compatible, so migration is mostly about re-evaluating which model tier you need — you may find that Sonnet 4.6 handles tasks you were previously using Opus 4.5 for.

Which Model to Start With

Default to Sonnet 4.6. Move to Opus 4.6 or 4.7 when you hit tasks where Sonnet keeps producing wrong answers or failing to catch edge cases. The progression is:

• Sonnet 4.6 — everyday development work
• Opus 4.6 — hard reasoning tasks, production-critical code
• Opus 4.7 — the hardest problems, largest contexts