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 procurement 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 |
| 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 | 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 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has GPT-5.5 Pro at 82.6 and Grok 4 at 76.7, with GPT-5.5 Pro ahead by 5.9 points; Google-Proof Q&A has GPT-5.5 Pro at 93.6 and Grok 4 at 87.5, with GPT-5.5 Pro ahead by 6.1 points; LiveCodeBench has GPT-5.5 Pro at 91 and Grok 4 at 79, with GPT-5.5 Pro ahead by 12 points. The largest visible gap is 12 points on LiveCodeBench, 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, GPT-5.5 Pro lists $30/1M input and $180/1M output tokens on the cheapest tracked provider, while Grok 4 lists $1.25/1M input and $2.50/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok 4 lower by about $73.38 per million blended tokens. Availability is 3 providers versus 4, so concentration risk also matters.
Choose GPT-5.5 Pro when coding workflow support and larger context windows are central to the workload. Choose Grok 4 when coding workflow support, lower input-token cost, and broader provider choice 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, GPT-5.5 Pro or Grok 4?
GPT-5.5 Pro supports 1.05m tokens, while Grok 4 supports 256k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, GPT-5.5 Pro or Grok 4?
Grok 4 is cheaper on tracked token pricing. GPT-5.5 Pro costs $30/1M input and $180/1M output tokens. Grok 4 costs $1.25/1M input and $2.50/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5.5 Pro or Grok 4 open source?
GPT-5.5 Pro is listed under Proprietary. Grok 4 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, GPT-5.5 Pro or Grok 4?
Both GPT-5.5 Pro and Grok 4 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, GPT-5.5 Pro or Grok 4?
Both GPT-5.5 Pro and Grok 4 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 GPT-5.5 Pro and Grok 4?
GPT-5.5 Pro is available on OpenAI API, OpenRouter, and Vercel AI Gateway. Grok 4 is available on Microsoft Foundry, OpenRouter, Replicate API, and xAI Console. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-07-10. Data sourced from public model cards and provider documentation.