Short answer
This comparison is Claude Sonnet 4.5 vs Claude Opus 4.5—not Opus 4.1 or Opus 5. Both models have a 200K-token context window and a 64K-token maximum output on Anthropic’s direct API. Sonnet 4.5 has lower per-token prices; Opus 4.5 is the higher-priced option if testing shows it performs better on your hardest tasks.
There is an important production caveat: as of November 10, 2026, Anthropic lists Sonnet 4.5 as deprecated, with retirement scheduled for November 30, 2026. Opus 4.5 is an active legacy model, with retirement not scheduled before November 24, 2026; Anthropic recommends considering migration to Opus 5.5. For a new, long-lived service, evaluate current models rather than building around either 4.5 version. (Sonnet 4.5 model documentation; Opus 4.5 model documentation)
If you need to choose between these two for an existing or short-term deployment, Sonnet is the lower-cost option for well-defined tasks. Consider Opus for higher-consequence work only if your own evaluation shows its results justify the added cost.
At a glance: direct Anthropic API
| Claude Sonnet 4.5 | Claude Opus 4.5 | |
|---|---|---|
| Dated API model ID | claude-sonnet-4-5-20250929 |
claude-opus-4-5-20251101 |
| API alias | claude-sonnet-4-5 |
claude-opus-4-5 |
| Context / maximum output | 200K / 64K tokens | 200K / 64K tokens |
| Input / output price | $3 / $15 per million tokens | $5 / $25 per million tokens |
| Input / output modalities | Text and images / text | Text and images / text |
| Lifecycle status | Deprecated; retires November 30, 2026 | Active (legacy); retirement not before November 24, 2026 |
These are Anthropic’s direct API identifiers and USD list prices, not third-party marketplace rates. Anthropic lists a 50% discount on input and output tokens through the Batch API for both models. Prompt caching has separate rates and conditions. Provider or cloud-platform pricing may differ; check the documentation for the channel you will use. (Sonnet 4.5 model documentation; Opus 4.5 model documentation)
What does the price difference mean in practice?
For aggregate usage across multiple requests totaling 10,000 input tokens and 2,000 output tokens, the listed charges are:
- Sonnet 4.5: (0.01 × $3) + (0.002 × $15) = $0.06.
- Opus 4.5: (0.01 × $5) + (0.002 × $25) = $0.10.
At those same token counts, Opus costs about 67% more than Sonnet. This is a token-charge comparison, not a cost-per-success result. Actual task costs depend on token use, retries, and whether one model produces more accepted results. Anthropic also lists prompt-cache rates: Sonnet costs $3.75 per million tokens for a five-minute cache write, $6 for a one-hour cache write, and $0.30 for a cache read; Opus costs $6.25, $10, and $0.50, respectively. (Sonnet 4.5 pricing and limits; Opus 4.5 pricing and limits)
Is Opus 4.5 better than Sonnet 4.5?
Anthropic’s Opus 4.5 launch announcement says Opus beat Sonnet 4.5 on Anthropic’s internal benchmarks and used fewer tokens to solve the same problems. That is a vendor-reported result, not a complete, reproducible scorecard for your production workload. (Anthropic’s Opus 4.5 announcement)
A frequently cited third-party code-review comparison is not an Opus 4.5 test: CodeRabbit evaluated Sonnet 4.5 against Opus 4.1 on 25 difficult pull requests. It reported a 41.5% “Important” comment share for Sonnet 4.5 and about 50% for Opus 4.1. The study’s Important-share measure includes comments that found the tracked bug or another significant issue; it is distinct from comment-level precision. These results are limited to that code-review evaluation and cannot establish Opus 4.5’s score or identify a winner for other tasks. (CodeRabbit’s benchmark and methodology)
Decision rule: If token cost matters most and errors are inexpensive, Sonnet 4.5 may fit an existing or short-term deployment. If errors are costly, test Opus 4.5 on those cases—but measure its benefit rather than assuming it. For either model, account for lifecycle status; Sonnet 4.5’s scheduled retirement makes it a poor foundation for a new service intended to run long-term.
How to choose for a production workload
Test both models on representative tasks using the same API channel, input data, instructions, tool definitions, and success criteria. Where practical, have reviewers assess outputs without knowing which model produced them. Track accepted-task rate, serious errors, input and output tokens, retries, and latency. Compare cost per accepted result, not just price per million tokens. This is a suggested evaluation method, not a test reported here.
A Sonnet-first, Opus-escalation approach may be worth evaluating in an existing system: send routine tasks to Sonnet and escalate only defined failure cases. Measure whether the route improves cost per accepted result, and account for Sonnet 4.5’s November 30, 2026 retirement. For a new service, test currently recommended models too and make it possible to change model IDs without rewriting the application. (Sonnet 4.5 lifecycle details; Anthropic models overview)
Sources
Claude Sonnet 4.5 — Claude Platform Docs
Claude Opus 4.5 — Claude Platform Docs
Models overview — Claude Platform Docs
Introducing Claude Opus 4.5 — Anthropic
Claude Sonnet 4.5: Better performance but a paradox — CodeRabbit