Claude Opus 5 vs Claude Sonnet 5

Both models share the same 1M-token context window, the same 128K maximum output and the same adaptive thinking, so the choice is not about capability ceilings. It is about price and task shape. Opus 5 costs $5 and $25 per million input and output tokens against Sonnet 5's $2 and $10 - two and a half times more in both directions. Anthropic positions Opus for complex agentic coding and long-running enterprise work and Sonnet as the best balance of speed and intelligence, and that is the honest dividing line: Sonnet is the default for everyday drafting, chat and code edits, while Opus pays for itself when a task runs for many steps and one wrong turn costs more than the token bill. One difference that rarely gets mentioned: Opus 5's reliable knowledge cutoff is May 2026 against Sonnet 5's January 2026, so Opus is roughly four months fresher on anything time-sensitive.