Claude Sonnet 5 Pricing Stays at $2/$10, But the New Tokenizer Generates Up to 30% More Tokens

My take: Today was the date when Claude Sonnet 5 pricing was set to rise 50%: from $2 to $3 per million input tokens, and from $10 to $15 per million output tokens. It did not happen. Anthropic made the pricing permanent in August, and that is good news for everyone building on the API.

But if you run Claude Sonnet 5 in production, there is something worth auditing. Sonnet 5's new tokenizer generates approximately 30% more tokens for the same text compared to earlier versions like Sonnet 4.6. That means even though the per-token price did not change, your real cost per task may have increased if you migrated from Sonnet 4.6 without adjusting your budget.

If you develop a product or service running on the Claude API, now is a good time to compare your token usage before and after the migration. The listed price stayed the same. Did your bill?