Claude 3.5 Sonnet vs o3-pro
Claude 3.5 Sonnet (2024) and o3-pro (2025) are frontier-tier reasoning models from Anthropic and OpenAI. Claude 3.5 Sonnet ships a 200k-token context window, while o3-pro ships a 200k-token context window. On Aider Polyglot, o3-pro leads by 33.3 pts. On pricing, Claude 3.5 Sonnet costs $3/1M input tokens versus $20/1M 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.
Claude 3.5 Sonnet is ~567% cheaper at $3/1M; pay for o3-pro only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude 3.5 Sonnet | o3-pro |
|---|---|---|
| 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 | $15/1M tokens | $80/1M tokens |
| Provider routes | 6 tracked | 3 tracked |
| Shared benchmarks | 1 shared | Aider Polyglot leader |
Decision tradeoffs
- Claude 3.5 Sonnet has the lower cheapest tracked output price at $15/1M tokens.
- Claude 3.5 Sonnet has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Claude 3.5 Sonnet for Coding, RAG, and Agents.
- o3-pro holds a shared-benchmark lead on Aider Polyglot, ahead by 33.3 points.
- o3-pro uniquely exposes Tool use in local model data.
- Local decision data tags o3-pro 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 3.5 Sonnet
$6,150
Cheapest tracked route/tier: GCP Vertex AI
o3-pro
$36,000
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $29,850. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- o3-pro is $65/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- o3-pro adds Tool use in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Claude 3.5 Sonnet is $65/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Tool use before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2024-06-20 | 2025-06-10 |
| Context window | 200k | 200k |
| Parameters | 70B | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2024-04 | 2025-08 |
Pricing and availability
| Pricing attribute | Claude 3.5 Sonnet | o3-pro |
|---|---|---|
| Input price | $3/1M tokens | $20/1M tokens |
| Output price | $15/1M tokens | $80/1M tokens |
| Providers |
Capabilities
| Capability | Claude 3.5 Sonnet | o3-pro |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | No | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Claude 3.5 Sonnet | o3-pro |
|---|---|---|
| Aider Polyglot | 51.6 | 84.9 |
Deep dive
On shared benchmark coverage, Aider Polyglot has Claude 3.5 Sonnet at 51.6 and o3-pro at 84.9, with o3-pro ahead by 33.3 points. The largest visible gap is 33.3 points on Aider Polyglot, 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 tool use: o3-pro. Both models share vision, multimodal input, reasoning mode, and function calling, 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 3.5 Sonnet lists $3/1M input and $15/1M output tokens on the cheapest tracked provider, while o3-pro lists $20/1M input and $80/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Claude 3.5 Sonnet lower by about $31.40 per million blended tokens. Availability is 6 providers versus 3, so concentration risk also matters.
Choose Claude 3.5 Sonnet when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose o3-pro when coding workflow support 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 3.5 Sonnet or o3-pro?
Claude 3.5 Sonnet supports 200k tokens, while o3-pro 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 3.5 Sonnet or o3-pro?
Claude 3.5 Sonnet is cheaper on tracked token pricing. Claude 3.5 Sonnet costs $3/1M input and $15/1M output tokens. o3-pro costs $20/1M input and $80/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude 3.5 Sonnet or o3-pro open source?
Claude 3.5 Sonnet is listed under Proprietary. o3-pro 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 3.5 Sonnet or o3-pro?
Both Claude 3.5 Sonnet and o3-pro expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Claude 3.5 Sonnet or o3-pro?
Both Claude 3.5 Sonnet and o3-pro expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run Claude 3.5 Sonnet and o3-pro?
Claude 3.5 Sonnet is available on GCP Vertex AI, AWS Bedrock, Anthropic, OpenRouter, and Microsoft Foundry. o3-pro is available on OpenRouter, OpenAI API, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-15. Data sourced from public model cards and provider documentation.