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 SWE-bench Verified, GPT-5.5 Pro leads by 3 pts. On pricing, Claude Sonnet 4.6 costs $3/1M input tokens versus $30/1M 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 Sonnet 4.6 is ~900% cheaper at $3/1M; pay for GPT-5.5 Pro only for coding workflow support.
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 | 5 shared | SWE-bench Verified 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 route 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 SWE-bench Verified, ahead by 3 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 <=272K tokens (standard)
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 |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-08 | 2025-12 |
Pricing and availability
| Pricing attribute | Claude Sonnet 4.6 | GPT-5.5 Pro |
|---|---|---|
| Input price | $3/1M tokens | $30/1M tokens |
| Output price | $15/1M tokens | $180/1M tokens |
| Providers |
Capabilities
| Capability | Claude Sonnet 4.6 | GPT-5.5 Pro |
|---|---|---|
| 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 | Yes | No |
| Parallel agents | Yes | No |
Benchmarks
| Benchmark | Claude Sonnet 4.6 | GPT-5.5 Pro |
|---|---|---|
| SWE-bench Verified | 79.6 | 82.6 |
| Google-Proof Q&A | 89.9 | 93.6 |
| LiveCodeBench | 80.0 | 91.0 |
| Terminal-Bench 2.0 | 59.1 | 82.7 |
| MCP-Atlas | 61.3 | 75.3 |
Continue comparing
- Claude Sonnet 4.6 vs GPT-5.5 Instant
- Claude Sonnet 4.6 vs Phi-4 Mini Flash Reasoning
- Claude Opus 4.6 vs GPT-5.5 Pro
- Claude Sonnet 4.6 vs DeepSeek V4 Flash
- Claude Sonnet 4.6 vs DeepSeek V4 Pro
- Claude Sonnet 4.6 vs Kimi K2.6
- Claude Sonnet 4.6 vs Composer 2.5
- Claude Sonnet 4.6 vs Gemini 3.5 Flash
- Claude Sonnet 4.6 vs GLM-5.1
- Claude Opus 4.7 vs Claude Sonnet 4.6
Popular comparisons for Claude Sonnet 4.6
Popular comparisons for GPT-5.5 Pro
Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.