What changed
An August 10, 2026 update to the Sonnet 5 announcement made the $2 input / $10 output per million tokens price permanent; the standard $3 / $15 pricing due on September 1 no longer applies. Anthropic also notes that Sonnet 5’s new tokenizer can produce about 1.0 to 1.35 times as many tokens for the same input as Sonnet 4.6.
Who it affects
API-key and cloud-provider users running Claude Code on Sonnet 5.
What to do
Update cost forecasts that assumed the September rise, and allow for the tokenizer change when comparing bills.