What is Sonnet 5?

Why a cheaper-per-token model can cost more per task: lower-capability models require more iterations and reasoning tokens to reach the same result, making the nominally expensive model the economical choice at the task level.

“However, Sonnet cost around $2 per task or 2.09 per task versus 1.94 for Opus. So, because Sonnet needed more iterations and more reasoning had to spend way more tokens to get to the same results, overall Opus, which is significantly on paper more expensive model, it was cheaper to operate.”

Opus 4.8 cost $1.94 per completed coding task vs $2.09 for Sonnet 5, despite Sonnet being cheaper per token (1.7x), because Sonnet required more iterations and reasoning tokens (Databricks benchmark).

“However, Sonnet cost around $2 per task or 2.09 per task versus 1.94 for Opus. So, because Sonnet needed more iterations and more reasoning had to spend way more tokens to get to the same results, overall Opus, which is significantly on paper more expensive model, it was cheaper to operate.”

Luna is the top closed model on OpenRouter with 40% more usage than Opus 5 and Sonnet 5 combined.

“It's now the top used closed model on the platform seeing 40% more use than Opus 5 and Sonnet 5 combined.”

Luna: new closed model reaching top usage on OpenRouter, surpassing Anthropic's Opus 5 and Sonnet 5 combined, making it a model to track for enterprise adoption signals.

“It's now the top used closed model on the platform seeing 40% more use than Opus 5 and Sonnet 5 combined.”

Sonnet 5, a nominally cheaper model, cost more per task than Opus 4.8 in practice because its high token usage erased the per-token price advantage.

“The overall run in fact cost more than opus 4.8.”