Claude Sonnet 4.6 vs GPT-5.5 Pro
Claude Sonnet 4.6 (2026) and GPT-5.5 Pro (2026) are frontier-tier reasoning models from Anthropic and OpenAI. Claude Sonnet 4.6 ships a 1m-token context window, while GPT-5.5 Pro ships a 1.05m-token context window. On Google-Proof Q&A, GPT-5.5 Pro leads by 3.7 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
GPT-5.5 Pro is safer overall; choose Claude Sonnet 4.6 when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Claude Sonnet 4.6 | GPT-5.5 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 | 1m | 1.05m |
| Cheapest output | $15/1M tokens | $180/1M tokens |
| Provider routes | 6 tracked | 3 tracked |
| Shared benchmarks | 2 shared | Google-Proof Q&A leader |
Decision tradeoffs
- Claude Sonnet 4.6 has the lower cheapest tracked output price at $15/1M tokens.
- Claude Sonnet 4.6 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Sonnet 4.6 uniquely exposes Computer use and Parallel agents in local model data.
- Local decision data tags Claude Sonnet 4.6 for Coding, RAG, and Agents.
- GPT-5.5 Pro holds a shared-benchmark lead on Google-Proof Q&A, ahead by 3.7 points.
- GPT-5.5 Pro has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Local decision data tags GPT-5.5 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 Sonnet 4.6
$6,150
Cheapest tracked route/tier: OpenRouter
GPT-5.5 Pro
$69,000
Cheapest tracked route/tier: OpenAI API
Estimated monthly gap: $62,850. 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.
- GPT-5.5 Pro is $165/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Computer use and Parallel agents before moving production traffic.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- Claude Sonnet 4.6 is $165/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Claude Sonnet 4.6 adds Computer use and Parallel agents in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-17 | 2026-04-23 |
| Context window | 1m | 1.05m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-08 | 2025-12 |
Pricing and availability
| Pricing attribute | Claude Sonnet 4.6 | GPT-5.5 Pro |
|---|---|---|
| Input price | $3/1M tokens |
|
| Output price | $15/1M tokens |
|
| Providers |
Capabilities
| Capability | Claude Sonnet 4.6 | GPT-5.5 Pro |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| 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 | Yes | No |
| Parallel agents | Yes | No |
Benchmarks
| Benchmark | Claude Sonnet 4.6 | GPT-5.5 Pro |
|---|---|---|
| Google-Proof Q&A | 89.9 | 93.6 |
| Humanity's Last Exam | 33.2 | 43.1 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Claude Sonnet 4.6 at 89.9 and GPT-5.5 Pro at 93.6, with GPT-5.5 Pro ahead by 3.7 points; Humanity's Last Exam has Claude Sonnet 4.6 at 33.2 and GPT-5.5 Pro at 43.1, with GPT-5.5 Pro ahead by 9.9 points. The largest visible gap is 9.9 points on Humanity's Last Exam, 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 is close: both models cover vision, multimodal input, reasoning mode, function calling, and tool use. That makes context budget, benchmark fit, and provider maturity more important than a simple checklist. If your application depends on one integration detail, verify it against the provider route you plan to use, not just the base model listing.
For cost, Claude Sonnet 4.6 lists $3/1M input and $15/1M output tokens on the cheapest tracked provider, while GPT-5.5 Pro lists tiered pricing: 0-272,000t is $30/1M input and $180/1M output; 272,000t+ is $60/1M input and $270/1M output. A 70/30 input-output blend puts Claude Sonnet 4.6 lower by about $68.40 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 6 providers versus 3, so concentration risk also matters.
Choose Claude Sonnet 4.6 when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose GPT-5.5 Pro when coding workflow support and larger context windows 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 Sonnet 4.6 or GPT-5.5 Pro?
GPT-5.5 Pro supports 1.05m tokens, while Claude Sonnet 4.6 supports 1m 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 Sonnet 4.6 or GPT-5.5 Pro?
Claude Sonnet 4.6 lists $3/1M input and $15/1M output tokens on the cheapest tracked provider. GPT-5.5 Pro lists tiered pricing: 0-272,000t is $30/1M input and $180/1M output; 272,000t+ is $60/1M input and $270/1M output. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Claude Sonnet 4.6 or GPT-5.5 Pro open source?
Claude Sonnet 4.6 is listed under Proprietary. GPT-5.5 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 Sonnet 4.6 or GPT-5.5 Pro?
Both Claude Sonnet 4.6 and GPT-5.5 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 Sonnet 4.6 or GPT-5.5 Pro?
Both Claude Sonnet 4.6 and GPT-5.5 Pro expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Claude Sonnet 4.6 and GPT-5.5 Pro?
Claude Sonnet 4.6 is available on OpenRouter, Anthropic, AWS Bedrock, GCP Vertex AI, and Microsoft Foundry. GPT-5.5 Pro is available on OpenAI API, OpenRouter, 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.