GPT-4o (05-13) vs GPT-5.5
GPT-4o (05-13) (2024) and GPT-5.5 (2026) are frontier reasoning models from OpenAI. GPT-4o (05-13) ships a 128k-token context window, while GPT-5.5 ships a 1.05m-token context window. On MMLU PRO, GPT-5.5 leads by 15.5 pts. On pricing, GPT-4o (05-13) costs $2.50/1M input tokens; GPT-5.5 ranges from $5 to $8/1M input tokens by tier. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
GPT-5.5 fits 8x more tokens; pick it for long-context work and GPT-4o (05-13) for tighter calls.
Decision scorecard
Local evidence first| Signal | GPT-4o (05-13) | GPT-5.5 |
|---|---|---|
| Best for | multimodal apps and provider-routed production | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 128k | 1.05m |
| Cheapest output | $10/1M tokens | $30/1M tokens |
| Provider routes | 4 tracked | 3 tracked |
| Shared benchmarks | 3 rows | MMLU PRO leader |
Decision tradeoffs
- GPT-4o (05-13) has the lower cheapest tracked output price at $10/1M tokens.
- GPT-4o (05-13) has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags GPT-4o (05-13) for Coding, RAG, and Agents.
- GPT-5.5 holds a shared-benchmark lead on MMLU PRO, ahead by 15.5 points.
- GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.5 uniquely exposes Reasoning, Function calling, and Tool use in local model data.
- Local decision data tags GPT-5.5 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-4o (05-13)
$4,500
Cheapest tracked route/tier: OpenAI API
GPT-5.5
$11,500
Cheapest tracked route/tier: OpenAI API 0-272K input tokens
Estimated monthly gap: $7,000. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenAI API and OpenRouter; start route-level A/B tests there.
- GPT-5.5 is $20/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GPT-5.5 adds Reasoning, Function calling, and Tool use in local capability data.
- Provider overlap exists on OpenAI API and OpenRouter; start route-level A/B tests there.
- GPT-4o (05-13) is $20/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning, Function calling, and Tool use before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2024-05-13 | 2026-04-23 |
| Context window | 128k | 1.05m |
| Parameters | 1.76T (8x222B MoE)* | — |
| Architecture | mixture of experts | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2023-10 | 2025-12 |
Pricing and availability
| Pricing attribute | GPT-4o (05-13) | GPT-5.5 |
|---|---|---|
| Input price | $2.50/1M tokens |
|
| Output price | $10/1M tokens |
|
| Providers |
Capabilities
| Capability | GPT-4o (05-13) | GPT-5.5 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | No | Yes |
| Tool use | No | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | GPT-4o (05-13) | GPT-5.5 |
|---|---|---|
| MMLU PRO | 72.5 | 88.1 |
| HumanEval | 90.2 | 94.2 |
| Massive Multitask Language Understanding | 88.7 | 92.4 |
Deep dive
On shared benchmark coverage, MMLU PRO has GPT-4o (05-13) at 72.5 and GPT-5.5 at 88.1, with GPT-5.5 ahead by 15.5 points; HumanEval has GPT-4o (05-13) at 90.2 and GPT-5.5 at 94.2, with GPT-5.5 ahead by 4 points; Massive Multitask Language Understanding has GPT-4o (05-13) at 88.7 and GPT-5.5 at 92.4, with GPT-5.5 ahead by 3.7 points. The largest visible gap is 15.5 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 reasoning mode: GPT-5.5, function calling: GPT-5.5, and tool use: GPT-5.5. Both models share vision, 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 $2.50/1M input and $10/1M output tokens on the cheapest tracked provider, while 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. A 70/30 input-output blend puts GPT-4o (05-13) lower by about $7.75 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-4o (05-13) when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose GPT-5.5 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 GPT-5.5?
GPT-5.5 supports 1.05m 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. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is cheaper, GPT-4o (05-13) or GPT-5.5?
GPT-4o (05-13) lists $2.50/1M input and $10/1M output tokens on the cheapest tracked provider. 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. 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-4o (05-13) or GPT-5.5 open source?
GPT-4o (05-13) is listed under Proprietary. GPT-5.5 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-4o (05-13) or GPT-5.5?
Both GPT-4o (05-13) and GPT-5.5 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-4o (05-13) or GPT-5.5?
Both GPT-4o (05-13) and GPT-5.5 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-4o (05-13) and GPT-5.5?
GPT-4o (05-13) is available on Azure OpenAI, OpenAI API, OpenRouter, and Replicate API. GPT-5.5 is available on OpenAI API, OpenRouter, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-08. Data sourced from public model cards and provider documentation.