Anthropic launched [Claude Sonnet 5](https://questloops.com/blog/claude-sonnet-5-explained-what-changed-what-it-costs-and-who-should-switch) on June 30, 2026 at introductory pricing of $2 per million input tokens and $10 per million output tokens. That rate disappears on August 31. Starting September 1, the same model costs $3 per million input tokens and $15 per million output tokens: a flat 50% increase on both sides of the ledger.
If you're running Claude Code, an agent pipeline, or anything else that burns through Sonnet tokens at volume, this is the kind of change that shows up on next month's invoice whether you noticed the announcement or not.
What actually changes on September 1
The jump isn't a restructuring or a new tier. It's a straight price increase on the same model. Anthropic billed Sonnet 5 as its most agentic Sonnet release yet, built for longer tool-use chains and coding workflows, and the intro pricing was clearly meant to pull developers off Opus 4.8 and Sonnet 4.5 during the launch window. That window is closing.
| Intro pricing (through Aug 31) | Standard pricing (from Sep 1) | |
|---|---|---|
| Input tokens | $2 / million | $3 / million |
| Output tokens | $10 / million | $15 / million |
| Increase | n/a | 50% on both |
For context, Claude Opus 5 sits at $5 per million input and $25 per million output, unchanged, with a fast mode that runs 2.5x faster at 2x the base cost. Sonnet 5 stays cheaper than Opus 5 even after the hike, but the gap narrows.
Why this matters more than a typical price change
A 50% increase applied evenly to input and output tokens is easy to miss if you're not tracking cost per request directly. Teams that scoped a project's economics around June's intro rate, and haven't rechecked since, will see their per-call cost jump by half with zero change to code or usage patterns. For high-volume agentic workloads, that adds up fast.
Anthropic is also running a separate, temporary usage boost for Claude Code subscribers (50% extra weekly usage), extended through August 19, plus a related bump tied to the Cowork rollout on mobile and web through August 5. Neither of those overlaps with the Sonnet 5 API pricing deadline, but if you're tracking Anthropic's calendar for cost planning, keep the two straight so you don't mistake a usage-limit change for a per-token price change.
What to actually do before August 31
Recalculate at $3/$15 before you promise a cost number to anyone, whether that's an internal budget or a client quote built on top of Sonnet 5 API costs. Re-run estimates for any high-volume agent: a workflow burning $200 a month in tokens today costs $300 a month starting September 1 with no other changes on your end. It's also worth checking whether Opus 5's fast mode is now close enough in effective cost to standard Sonnet 5 to be worth a second look, since the gap between the two tiers just shrank. And don't confuse any of this with the Claude Code weekly usage boost, which runs on its own separate calendar.
FAQ
**Does this affect Claude.ai chat subscriptions?** No. This is API/token pricing for developers building on Sonnet 5, separate from consumer Claude Pro or Max subscription plans.
**Is there any way to keep the old rate?** No. The intro rate was always temporary and Anthropic hasn't signaled any extension or grandfathering for existing usage.
None of this has a workaround. The rate was always temporary, and August 31 was always going to be the date it ended. The only real move is making sure anything you built around $2/$10 pricing gets re-priced before the invoice does it for you.
