GPT-5.5 Pro vs Grok 4
GPT-5.5 Pro (2026) and Grok 4 (2025) are frontier-tier reasoning models from OpenAI and xAI. GPT-5.5 Pro ships a 1.05m-token context window, while Grok 4 ships a 256k-token context window. On SWE-bench Verified, GPT-5.5 Pro leads by 5.9 pts. On pricing, Grok 4 costs $1.25/1M 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.
Grok 4 is ~2300% cheaper at $1.25/1M; pay for GPT-5.5 Pro only for coding workflow support.
Decision scorecard
Local evidence first| Signal | GPT-5.5 Pro | Grok 4 |
|---|---|---|
| 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 | 1.05m | 256k |
| Cheapest output | $180/1M tokens | $2.50/1M tokens |
| Provider routes | 3 tracked | 4 tracked |
| Shared benchmarks | SWE-bench Verified leader | 3 shared |
Decision tradeoffs
- GPT-5.5 Pro holds a shared-benchmark lead on SWE-bench Verified, ahead by 5.9 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.
- Grok 4 has the lower cheapest tracked output price at $2.50/1M tokens.
- Grok 4 has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags Grok 4 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.
GPT-5.5 Pro
$69,000
Cheapest tracked route/tier: OpenAI API <=272K tokens (standard)
Grok 4
$1,625
Cheapest tracked route/tier: xAI Console
Estimated monthly gap: $67,375. 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.
- Grok 4 is $178/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- GPT-5.5 Pro is $178/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-23 | 2025-07-09 |
| Context window | 1.05m | 256k |
| 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 | - |
Pricing and availability
| Pricing attribute | GPT-5.5 Pro | Grok 4 |
|---|---|---|
| Input price | $30/1M tokens | $1.25/1M tokens |
| Output price | $180/1M tokens | $2.50/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.5 Pro | Grok 4 |
|---|---|---|
| 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 | GPT-5.5 Pro | Grok 4 |
|---|---|---|
| SWE-bench Verified | 82.6 | 76.7 |
| Google-Proof Q&A | 93.6 | 87.5 |
| LiveCodeBench | 91.0 | 79.0 |
Continue comparing
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Last reviewed: 2026-07-10. Data sourced from public model cards and provider documentation.