GPT-4o (05-13) vs Grok 4
GPT-4o (05-13) (2024) and Grok 4 (2026) are frontier reasoning models from OpenAI and xAI. GPT-4o (05-13) ships a 128K-token context window, while Grok 4 ships a 256k-token context window. On MMLU PRO, Grok 4 leads by 14.5 pts. On pricing, GPT-4o (05-13) costs $2.5/1M input tokens versus $3/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Pick Grok 4 for general evaluation; GPT-4o (05-13) is better when coding workflow support matters more.
Specs
| Specification | ||
|---|---|---|
| Released | 2024-05-13 | 2026-03-01 |
| Context window | 128K | 256k |
| Parameters | 1.76T (8x222B MoE)* | — |
| Architecture | mixture of experts | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2023-10 | - |
Pricing and availability
| Pricing attribute | GPT-4o (05-13) | Grok 4 |
|---|---|---|
| Input price | $2.5/1M tokens | $3/1M tokens |
| Output price | $10/1M tokens | $15/1M tokens |
| Providers |
Capabilities
| Capability | GPT-4o (05-13) | Grok 4 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | No | Yes |
| Tool use | No | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | GPT-4o (05-13) | Grok 4 |
|---|---|---|
| MMLU PRO | 72.5 | 87.0 |
Deep dive
On shared benchmark coverage, MMLU PRO has GPT-4o (05-13) at 72.5 and Grok 4 at 87, with Grok 4 ahead by 14.5 points. The largest visible gap is 14.5 points on MMLU 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 vision: GPT-4o (05-13), reasoning mode: Grok 4, function calling: Grok 4, and tool use: Grok 4. Both models share multimodal input, structured outputs, and code execution, 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-4o (05-13) lists $2.5/1M input and $10/1M output tokens, while Grok 4 lists $3/1M input and $15/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts GPT-4o (05-13) lower by about $1.85 per million blended tokens. Availability is 4 providers versus 3, so concentration risk also matters.
Choose GPT-4o (05-13) when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose Grok 4 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, GPT-4o (05-13) or Grok 4?
Grok 4 supports 256k tokens, while GPT-4o (05-13) supports 128K 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-4o (05-13) or Grok 4?
GPT-4o (05-13) is cheaper on tracked token pricing. GPT-4o (05-13) costs $2.5/1M input and $10/1M output tokens. Grok 4 costs $3/1M input and $15/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-4o (05-13) or Grok 4 open source?
GPT-4o (05-13) 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-4o (05-13) or Grok 4?
GPT-4o (05-13) has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, GPT-4o (05-13) or Grok 4?
Both GPT-4o (05-13) 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-4o (05-13) and Grok 4?
GPT-4o (05-13) is available on Azure OpenAI, OpenAI API, OpenRouter, and Replicate API. Grok 4 is available on Microsoft Foundry, OpenRouter, and Replicate API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.