Claude Opus 4.5 vs o3
Claude Opus 4.5 (2025) and o3 (2025) are frontier-tier reasoning models from Anthropic and OpenAI. Claude Opus 4.5 ships a 200k-token context window, while o3 ships a 200k-token context window. On SWE-bench Verified, Claude Opus 4.5 leads by 9.2 pts. On pricing, o3 costs $2/1M input tokens versus $5/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
o3 is ~150% cheaper at $2/1M; pay for Claude Opus 4.5 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.5 | o3 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 200k | 200k |
| Cheapest output | $25/1M tokens | $8/1M tokens |
| Provider routes | 6 tracked | 3 tracked |
| Shared benchmarks | SWE-bench Verified leader | 6 shared |
Decision tradeoffs
- Claude Opus 4.5 holds a shared-benchmark lead on SWE-bench Verified, ahead by 9.2 points.
- Claude Opus 4.5 has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags Claude Opus 4.5 for Coding, RAG, and Agents.
- o3 holds a shared-benchmark lead on Google-Proof Q&A, ahead by 0.7 points.
- o3 has the lower cheapest tracked output price at $8/1M tokens.
- Local decision data tags o3 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Opus 4.5
$10,250
Cheapest tracked route/tier: Microsoft Foundry
o3
$3,600
Cheapest tracked route/tier: OpenAI API
Estimated monthly gap: $6,650. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- o3 is $17/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- Claude Opus 4.5 is $17/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-01 | 2025-04-16 |
| Context window | 200k | 200k |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-12 | 2024-06 |
Pricing and availability
| Pricing attribute | Claude Opus 4.5 | o3 |
|---|---|---|
| Input price | $5/1M tokens | $2/1M tokens |
| Output price | $25/1M tokens | $8/1M tokens |
| Providers |
Capabilities
| Capability | Claude Opus 4.5 | o3 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Claude Opus 4.5 | o3 |
|---|---|---|
| SWE-bench Verified | 80.9 | 71.7 |
| Google-Proof Q&A | 87.0 | 87.7 |
| Massive Multi-discipline Multimodal Understanding | 80.7 | 82.9 |
| Chatbot Arena | 1466.0 | 1412.0 |
| Aider Polyglot | 72.0 | 81.3 |
| MMMU Pro | 73.9 | 76.4 |
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Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.