Claude Sonnet 5 stays at $2 per million input tokens and $10 per million output tokens, and the increase to $3/$15 scheduled for September 1, 2026 will not happen.
Sticker rates now sit within cents of each other across vendors, so tokenizer behaviour and caching discipline decide the bill more than the headline price.
Claude models from version 4.7 onward use a tokenizer that produces roughly 30% more tokens for the same text (Anthropic, 2026), which changes the real cost of a like-for-like comparison.