Claude Sonnet 5 migration: the September 1, 2026 price cliff and the 30% tokenizer jump to plan for
Claude Sonnet 5 launched on June 30, 2026 at introductory $2/$10 pricing through August 31. On September 1 it moves to $3/$15, and a new tokenizer already counts about 30% more tokens for the same text. Here is the cost
