Claude Sonnet vs Opus in 2026
When Sonnet 5 is enough and when you still pay for Opus 5. Links into the live pair page.
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 requires deep multi-step computer-use and high reasoning, pay Opus and measure on your own eval set.
Ready to evaluate your stack?
Calculate your optimal model weights with Stack Engine or compare top models head-to-head.
Related guides
Same topic, next level of detail.
Explore More AI Intelligence Tools
Pairwise Model Comparisons
Compare any two models on our category ratings, speed classes and token pricing.
Curated 'Best-Of' Indexes
Targeted rankings for Best Coding LLMs, Best Cheap APIs, Shortest Wait, and top-tier models.
AI Hardware Calculator
Interactive VRAM calculator, quantization levels (FP16, Q8, Q4), KV cache context, and local hardware fit.
Live Market Intelligence
Live audit trail of benchmark updates, new model releases, and API price cuts.
Interactive Model Finder
Answer 5 quick questions to compute deterministic model recommendations for your use case.
Methodology & Standards
How a CompareLLM rating is computed, what evidence it admits, and how prices and speed classes are recorded.