GPT-5.5 vs Grok 4.5
GPT-5.5 (2026) and Grok 4.5 (2026) compare a standalone API model against a coding-specialized model. GPT-5.5 ships a 1.05m-token context window, while Grok 4.5 ships a 500k-token context window. On SWE-bench Pro, Grok 4.5 leads by 6.1 pts. On pricing, GPT-5.5 ranges from $5 to $8/1M input tokens by tier; Grok 4.5 ranges from $2 to $4/1M input tokens by tier. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: GPT-5.5 is standalone API model, while Grok 4.5 is coding-specialized model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | GPT-5.5 | Grok 4.5 |
|---|---|---|
| Product type | Standalone API model | Coding-specialized model |
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | custom coding agents, code generation, and tool loops |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1.05m | 500k |
| Cheapest output | $30/1M tokens | $6/1M tokens |
| Provider routes | 4 tracked | 3 tracked |
| Shared benchmarks | 2 shared | SWE-bench Pro leader |
Decision tradeoffs
- GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.5 has broader tracked provider coverage for fallback and procurement flexibility.
- GPT-5.5 uniquely exposes Structured outputs in local model data.
- Local decision data tags GPT-5.5 for Coding, RAG, and Agents.
- Grok 4.5 holds a shared-benchmark lead on SWE-bench Pro, ahead by 6.1 points.
- Grok 4.5 has the lower cheapest tracked output price at $6/1M tokens.
- Local decision data tags Grok 4.5 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
$11,500
Cheapest tracked route/tier: OpenAI API 0-272K input tokens
Grok 4.5
$3,100
Cheapest tracked route/tier: xAI Console <=200K prompt tokens
Estimated monthly gap: $8,400. 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.
- Grok 4.5 is $24/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Structured outputs before moving production traffic.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.5 is $24/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GPT-5.5 adds Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-23 | 2026-07-08 |
| Context window | 1.05m | 500k |
| Parameters | — | — |
| Architecture | 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 | Grok 4.5 |
|---|---|---|
| Input price |
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| Output price |
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| Providers |
Capabilities
| Capability | GPT-5.5 | Grok 4.5 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | No |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| SWE-bench Pro | 58.6 | 64.7 |
| Terminal-Bench 2.1 | 78.2 | 83.3 |
Deep dive
On shared benchmark coverage, SWE-bench Pro has GPT-5.5 at 58.6 and Grok 4.5 at 64.7, with Grok 4.5 ahead by 6.1 points; Terminal-Bench 2.1 has GPT-5.5 at 78.2 and Grok 4.5 at 83.3, with Grok 4.5 ahead by 5.1 points. The largest visible gap is 6.1 points on SWE-bench Pro, 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 structured outputs: GPT-5.5. 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, GPT-5.5 lists tiered pricing: 0-272K input tokens is $5/1M input and $30/1M output; 272K+ input tokens is $8/1M input and $36/1M output, while Grok 4.5 lists tiered pricing: <=200K prompt tokens is $2/1M input and $6/1M output; >200K prompt tokens is $4/1M input and $12/1M output. A 70/30 input-output blend puts Grok 4.5 lower by about $9.30 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 4 providers versus 3, so concentration risk also matters.
Choose GPT-5.5 when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Grok 4.5 when coding workflow support and lower cheapest-tier input-token cost 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 or Grok 4.5?
GPT-5.5 supports 1.05m tokens, while Grok 4.5 supports 500k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is cheaper, GPT-5.5 or Grok 4.5?
GPT-5.5 lists tiered pricing: 0-272K input tokens is $5/1M input and $30/1M output; 272K+ input tokens is $8/1M input and $36/1M output. Grok 4.5 lists tiered pricing: <=200K prompt tokens is $2/1M input and $6/1M output; >200K prompt tokens is $4/1M input and $12/1M 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 GPT-5.5 or Grok 4.5 open source?
GPT-5.5 is listed under Proprietary. Grok 4.5 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 or Grok 4.5?
Both GPT-5.5 and Grok 4.5 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 or Grok 4.5?
Both GPT-5.5 and Grok 4.5 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 and Grok 4.5?
GPT-5.5 is available on OpenAI API, OpenRouter, Vercel AI Gateway, and AWS Bedrock. Grok 4.5 is available on xAI Console, OpenRouter, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-07-09. Data sourced from public model cards and provider documentation.