Correction: Sonnet 5 is not getting more expensive on September 1

Since June 30 we have published — in the cost calculator, in a fast take, and in our own working notes as a hard-dated reminder — that Claude Sonnet 5's $2/$10 per million was introductory pricing that would rise to $3/$15 on September 1. Anthropic has cancelled that increase. The introductory rate is now the standard rate. We were going to act on the old date; this is us correcting it before we did.

Verdict: The September 1 increase we told you to plan for is cancelled — $2/$10 is now permanent

The take

The change, quoted verbatim from Anthropic's own rate card at platform.claude.com: "The $2/$10 per million input/output token pricing for Claude Sonnet 5, announced at launch as introductory pricing through August 31, 2026, is now the standard price. The previously scheduled increase to $3/$15 per million input/output tokens on September 1, 2026 will not occur." No ambiguity, no phase-in. Sonnet 5 is a $2/$10 model permanently.

What that changes for the local-versus-cloud question, which is the only reason we track cloud prices at all: Sonnet is the tier most people actually pay for when they reach for the cloud, so it is the most relevant comparator for "is buying hardware worth it?". Our June coverage said the intro discount tilted the short-term maths toward cloud and that break-even "snaps back" on September 1. It does not snap back. The cheaper cloud baseline is permanent, which means the payback period on a local rig stays longer than we told you it would — and that is the honest direction of the correction, not the flattering one. Combined with OpenAI cutting Luna 80% and Terra 20% on July 30, the cloud floor has moved down twice in six weeks while GPU prices moved up.

What we changed: the `claudeSonnet5Api` note in the cost calculator now carries the correction in place rather than a silent edit, so anyone who read the old claim can see what happened and why. The blended $6 average per 1M is unchanged — it was already priced at the intro rate — so no number in the calculator moves; what moves is the forward-looking claim attached to it. We also added a test that asserts Sonnet 5 costs $60 per 10M tokens and explicitly **not** $90, because the most likely way this breaks in future is a session finding our old "bump to $3/$15 after Aug 31" reminder and dutifully acting on it. The test is there to stop that.

Why publish a whole take on someone else's price not changing: because we told readers it would, in a tool they use to make a purchase decision, with a specific date attached. A correction that only appears as a quiet diff is not a correction. This is the same reason our quarterly rollups carry a "what we got wrong" section — a currency claim is only worth something if the misses are as visible as the hits.

Where this fits

Models: DeepSeek V4-Pro · Kimi K3 (2.8T-A50B)

Hardware: NVIDIA RTX 5090 · NVIDIA RTX 4090

Sources

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