Claude Opus 5 vs Claude Sonnet 5: flagship or workhorse for your Claude stack?
Sonnet 5 for almost everything. Reserve Opus 5 for the hardest multi-step planning, longest-context agentic chains, or workloads where Sonnet 5's quality actually falls short and a wrong answer costs more than the 2.5x premium.
The two top Claude tiers - same lineage, very different price points.
Anthropic's Claude lineup has two tiers buyers weigh against each other for almost any non-Haiku workload. Opus 5 is the deep-reasoning flagship, Sonnet 5 is the coding-and-agentic workhorse. Sonnet 5 is 2.5x cheaper on input and 2.5x cheaper on output - meaning the decision is rarely about price alone.
By TechCompare · Updated
Cost Comparison
Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.Prices are fetched live from OpenRouter and may include temporary promotional discounts not accounted for in our article and comparison figures.
Side-by-side specs
| Spec | Claude Opus 5 | Claude Sonnet 5 |
|---|---|---|
| Input Cost (per M) | $5.00 | $2.00 (better on this spec) |
| Output Cost (per M) | $25.00 | $10.00 (better on this spec) |
| Cached Input (per M) | $0.50 | $0.20 (better on this spec) |
| Batch Discount | 50% | 50% |
| Context Window | 1M | 1M |
How they differ
Claude Opus 5 is priced at $5.00 per million input tokens and $25.00 per million output tokens, with a 90% caching discount ($0.50 per million) and a 50% batch discount. Claude Sonnet 5 is priced at $2.00 per million input tokens and $10.00 per million output tokens, with the same 90% caching discount ($0.20 per million) and 50% batch. Both share the 1M context window. For a 100K input + 10K output request, Opus costs $0.75 vs Sonnet's $0.30 - a 2.5x per-call premium. Sonnet 5's capability now covers the bulk of coding and agentic workloads that used to need Opus, which is when the Opus premium becomes hard to justify for general-purpose use.
Verdict
The cost ratio is a clean 2.5x on every row: $2.00/M input against $5.00, $10.00/M output against $25.00, $0.20/M cached input against $0.50. Batch ties at 50% on both and context ties at 1M, so neither side has a discount lever to flip. Call it $0.30 vs $0.75 on a 100K input + 10K output request, which compiles to about a $450K gap per million calls. Reach for Opus 5 only when Sonnet 5 demonstrably stalls on hardest-tier reasoning work.
Which should you pick?
Choose Claude Opus 5
Hardest-tier reasoning: long-horizon agentic planning, complex code synthesis across many files, scientific analysis. The Opus premium earns its keep only when Sonnet 5 demonstrably stalls.
Choose Claude Sonnet 5
Everyday coding, RAG, customer-facing chat, and most agentic workflows. Sonnet 5 is the new default for workloads that used to need Opus.