Claude Sonnet 5: Release, Pricing & How It Compares to Fable 5

On June 30, 2026, Anthropic shipped Claude Sonnet 5 (claude-sonnet-5) — the newest model in its mid-tier Sonnet line and, in the company's framing, its most agentic Sonnet yet. A day later, Claude Fable 5 returned globally from its export-control suspension. Here is what Sonnet 5 is, what it costs, and when to reach for it instead of Fable 5.

Claude Sonnet 5: the short answer

Sonnet 5 plans multi-step work, drives browsers and terminals, and runs autonomously at a level that recently required larger, more expensive models. It ships with a 1M-token context window and up to 128K output tokens, and lands close to Opus 4.8 quality for far less money. See the full spec sheet on the Claude Sonnet 5 model page.

Pricing

Sonnet 5 launched at an introductory $2 / $10 per million input/output tokens, and Anthropic has since made that rate the standard price: the increase to $3 / $15 scheduled for September 1, 2026 will not occur (checked 2026-09-19). $3 / $15 stays as Sonnet 4.6's list price.

One catch: Sonnet 5 uses a new tokenizer that produces roughly 30% more tokens for the same text. So even though Sonnet 5's standard rate now sits below 4.6's $3 / $15, an equivalent request can still cost more in practice. Budget with the token inflation in mind.

Availability

Day-one availability was unusually broad:

• Default model for Free and Pro on claude.ai; available to Max, Team, and Enterprise
• Claude Code and the Claude API as claude-sonnet-5
• AWS Bedrock, Google Vertex, Microsoft Foundry
• Third-party tools: Cursor, VS Code, GitHub Copilot, OpenRouter

Migration: three behavior changes

If you are moving from Sonnet 4.6, update the model ID and note:

1. Adaptive thinking is on by default.
2. Manual extended thinking is removed — thinking: {type: "enabled", budget_tokens: N} now returns a 400 error.
3. Sampling parameters are locked — setting temperature, top_p, or top_k to non-default values returns a 400 error.

Priority Tier is not available on Sonnet 5.

Sonnet 5 vs Fable 5: which to use

Rule of thumb: start on Sonnet 5 for everyday agentic coding — it's five times cheaper on input and output. Escalate to Claude Fable 5 only when peak reasoning quality justifies the cost. Since a well-structured prompt ports across the whole Claude lineup, keep one portable system prompt and switch models per task.

Summary

• Released June 30, 2026 as claude-sonnet-5
• $2 / $10 is now the standard price — the scheduled rise to $3 / $15 was cancelled
• 1M context, 128K output, adaptive thinking on by default
• New tokenizer counts ~30% more tokens — budget accordingly
• Pick Sonnet 5 for volume and speed; Fable 5 for peak capability

Independent analysis, last updated July 1, 2026. Official sources always win on conflict — see anthropic.com/news for the primary announcements.