In short
Opus is smarter; Sonnet is faster and cheaper. Use Opus for one-shot complex tasks (refactors, deep analysis, agent workflows). Use Sonnet for high-volume tasks (writing many drafts, batch processing, fast iteration). On Claude Pro, you get both; switch based on the task.
Claude Opus
by Anthropic · since 2024
Claude Sonnet
by Anthropic · since 2024
Capability scorecard
Scored 0-10. Higher is better.
Opus edges Sonnet on every benchmark, but the gap is small for most tasks.
Sonnet is ~3x faster and feels snappy; Opus has noticeable thinking pauses.
Opus: $15/$75 per M tokens. Sonnet: $3/$15. 5x cheaper.
Opus wins on complex refactors; Sonnet is great for daily coding.
Nearly identical. Both produce excellent long-form prose.
Opus handles complex multi-step better; Sonnet trips on harder logic.
Opus plans more reliably in agentic loops (Claude Code, Computer Use).
Both support 200k+ tokens; Opus 4.7 extends to 500k.
Opus is heavily capped on Pro; Sonnet is generous.
Cost and speed make Sonnet the only choice at scale.
When to pick which
Real use cases, decided by quality (not vendor bias).
Refactoring a 50-file React codebase
Opus handles complex multi-file coordination more reliably.
Drafting 20 marketing emails in a sitting
Sonnet is fast enough to iterate quickly; Opus would burn your quota.
Analyzing a 200-page legal contract
Opus catches subtle clauses Sonnet may gloss over.
Batch translating 1,000 product descriptions
Sonnet via API. Opus would be 5x more expensive for marginal quality gain.
Running a Claude Code agent on a big task
Opus's planning is more reliable across long agent loops.
Daily Q&A with your knowledge base
Sonnet is plenty good and 5x cheaper at scale.
Drafting a research paper
Opus produces tighter, more nuanced academic prose.
Powering a customer support chatbot
Sonnet at $3/M input tokens is the only sane choice for high-volume.
The verdict
Default to Sonnet. Switch to Opus when (a) the task is one-shot and quality-critical, (b) you're running an agent that needs to plan multi-step, or (c) you've tried Sonnet and the output is just barely off. For 80% of daily work, Sonnet is genuinely the right pick.
Frequently asked questions
Is Opus always better than Sonnet?▾
Slightly, on every benchmark, but the gap is small for most real-world tasks. For everyday work, the difference is rarely noticeable.
When should I switch from Sonnet to Opus?▾
When Sonnet's output is "almost right but not quite," when you're running an agent that needs to plan multi-step, or when the task is one-shot and quality is critical.
Why is Opus rate-limited on Pro?▾
Opus uses significantly more compute. Anthropic caps it to keep the $20/mo Pro tier sustainable. Max tier ($100/mo) raises the cap 20x.
Is Sonnet good enough for coding?▾
For 80% of daily coding tasks, yes. For complex refactors or architecture changes, switch to Opus.
Does the API have different pricing?▾
Yes. Opus is $15/$75 per M tokens (input/output). Sonnet is $3/$15. Opus is 5x more expensive, which matters at scale.
What about Haiku?▾
Haiku (Claude 4.5 Haiku in 2026) is the cheapest, fastest model, great for high-volume simple tasks. Use Haiku for classifications and tagging; Sonnet for substantive work; Opus for the hardest tasks.
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