Claude Opus 4.5 vs o3 Mini
Claude Opus 4.5 (2025) and o3 Mini (2025) are frontier-tier reasoning models from Anthropic and OpenAI. Claude Opus 4.5 ships a 200k-token context window, while o3 Mini ships a 200k-token context window. On MMLU PRO, Claude Opus 4.5 leads by 9.8 pts. On pricing, o3 Mini costs $1.10/1M 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 Mini is ~355% cheaper at $1.10/1M; pay for Claude Opus 4.5 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.5 | o3 Mini |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, tool-calling agents, and provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 200k | 200k |
| Cheapest output | $25/1M tokens | $4.40/1M tokens |
| Provider routes | 6 tracked | 4 tracked |
| Shared benchmarks | MMLU PRO leader | 5 rows |
Decision tradeoffs
- Claude Opus 4.5 holds a shared-benchmark lead on MMLU PRO, ahead by 9.8 points.
- Claude Opus 4.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Opus 4.5 uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags Claude Opus 4.5 for Coding, RAG, and Agents.
- o3 Mini has the lower cheapest tracked output price at $4.40/1M tokens.
- Local decision data tags o3 Mini 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 Mini
$1,980
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $8,270. 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 Mini is $20.60/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision and Multimodal before moving production traffic.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- Claude Opus 4.5 is $20.60/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Opus 4.5 adds Vision and Multimodal in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-01 | 2025-01-31 |
| Context window | 200k | 200k |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-12 | 2025-04 |
Pricing and availability
| Pricing attribute | Claude Opus 4.5 | o3 Mini |
|---|---|---|
| Input price | $5/1M tokens | $1.10/1M tokens |
| Output price | $25/1M tokens | $4.40/1M tokens |
| Providers |
Capabilities
| Capability | Claude Opus 4.5 | o3 Mini |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| 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 Mini |
|---|---|---|
| MMLU PRO | 88.9 | 79.1 |
| SWE-bench Verified | 80.9 | 49.3 |
| Google-Proof Q&A | 87.0 | 79.7 |
| Chatbot Arena | 1466.0 | 1335.0 |
| Aider Polyglot | 72.0 | 60.4 |
Deep dive
On shared benchmark coverage, MMLU PRO has Claude Opus 4.5 at 88.9 and o3 Mini at 79.1, with Claude Opus 4.5 ahead by 9.8 points; SWE-bench Verified has Claude Opus 4.5 at 80.9 and o3 Mini at 49.3, with Claude Opus 4.5 ahead by 31.6 points; Google-Proof Q&A has Claude Opus 4.5 at 87 and o3 Mini at 79.7, with Claude Opus 4.5 ahead by 7.3 points. The largest visible gap is 31.6 points on SWE-bench Verified, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Claude Opus 4.5 and multimodal input: Claude Opus 4.5. Both models share reasoning mode, function calling, tool use, and structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Opus 4.5 lists $5/1M input and $25/1M output tokens on the cheapest tracked provider, while o3 Mini lists $1.10/1M input and $4.40/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts o3 Mini lower by about $8.91 per million blended tokens. Availability is 6 providers versus 4, so concentration risk also matters.
Choose Claude Opus 4.5 when coding workflow support and broader provider choice are central to the workload. Choose o3 Mini when coding workflow support and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Opus 4.5 or o3 Mini?
Claude Opus 4.5 supports 200k tokens, while o3 Mini supports 200k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Opus 4.5 or o3 Mini?
o3 Mini is cheaper on tracked token pricing. Claude Opus 4.5 costs $5/1M input and $25/1M output tokens. o3 Mini costs $1.10/1M input and $4.40/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Opus 4.5 or o3 Mini open source?
Claude Opus 4.5 is listed under Proprietary. o3 Mini is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Opus 4.5 or o3 Mini?
Claude Opus 4.5 has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Claude Opus 4.5 or o3 Mini?
Claude Opus 4.5 has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Opus 4.5 and o3 Mini?
Claude Opus 4.5 is available on Microsoft Foundry, Anthropic, GCP Vertex AI, AWS Bedrock, and OpenRouter. o3 Mini is available on OpenRouter, Azure OpenAI, OpenAI API, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-04. Data sourced from public model cards and provider documentation.