Claude Sonnet 5’s introductory pricing ends August 31, 2026. [Anthropic’s](#/company/anthropic) own pricing documentation confirms the model reverts from $2 per million input tokens and $10 per million output tokens to a standard $3 and $15 on September 1 — a 50% increase on both rates, applied the same day, with no phase-in.
The higher number isn’t actually higher than what Anthropic already charges elsewhere in its lineup: $3 per million input tokens and $15 per million output tokens is identical to Claude Sonnet 4.6’s standard rate. Anthropic’s pricing page frames Sonnet 5’s launch price as introductory, not as a permanent discount — the September rate simply brings Sonnet 5 into line with where Sonnet models have priced since before this one existed.
What doesn’t return to the old baseline is the token count itself. Claude 4.7 and later models, Sonnet 5 included, use a newer [tokenizer](#/dictionary) that Anthropic’s own documentation says produces roughly 30% more tokens for the same text than the tokenizer Sonnet 4.6 and earlier models used. A developer who kept a workload’s per-token price flat by switching from 4.6 to 5 was never actually paying an unchanged bill — more tokens were quietly doing the same job underneath a sticker price that looked stable. From September 1, that workload faces both effects at once: the per-token rate rises 50%, on a token count that’s already roughly 30% higher than the equivalent request would have produced on the older model. Neither change is hidden — Anthropic states both on the same pricing page — but they’re easy to read as one 50% increase rather than two separate cost drivers stacking on top of each other.
Claude Sonnet 5, two separate cost changes stacking
- $2 → $3 · per MTok input
- Introductory-to-standard rate change
Includes: A flat 50% increase on the base input-token price
Excludes: Cache-write and cache-read pricing, which move by the same proportion but aren’t shown here - $10 → $15 · per MTok output
- Introductory-to-standard rate change
Includes: A flat 50% increase on the base output-token price
Excludes: Fast-mode or batch-API pricing, which follow separate schedules - ~30% more · tokens per request
- Tokenizer effect, already in effect since launch
Includes: A structural change in how Sonnet 5 counts the same text, unrelated to the September price change
Excludes: An exact per-workload figure — Anthropic states the increase ‘depends on the content and workload shape’
- Claude Sonnet 5’s $2/$10 per-million-token launch pricing ends August 31, reverting to $3/$15 on September 1.
- That’s a 50% per-token rate increase on both input and output tokens, applied the same day.
- A separate tokenizer change already makes Sonnet 5 produce about 30% more tokens per request than Sonnet 4.6 did.
- The new standard rate matches what Sonnet 4.6 already charged — the sticker price isn’t rising past the old model’s.
- Caveat: a like-for-like task can still cost meaningfully more in practice, because more tokens now bill at that higher rate.