CompareLLM Practical Guide
Updated 2026-08-16Claude Sonnet vs Opus in 2026
When Sonnet 5 is enough and when you still pay for Opus 5. Links into the live pair page.
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Same family, different invoice
Sonnet is the workhorse. Opus is the “this repo is on fire” model. On CompareLLM, open the current Sonnet vs Opus pair — today that is usually Sonnet 5 vs Opus 5 — and look at SWE-bench, Elo, and output $/1M together.
If the coding delta is small and you run thousands of agent turns a day, Sonnet (or Terra / Flash) is the default. If the task is a long-horizon computer-use job, pay Opus and measure on your own eval set.
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