Claude Sonnet 5 pricing goes up September 1 but the tokenizer change means your costs could nearly double even if you are doing the same work.

Sonnet 5 has a new tokenizer and the same content that generated X tokens on previous claude versions now generates 1.0 to 1.35x more tokens on sonnet 5 so if you are migrating workloads from older models or comparing costs, you are paying 50% more per token