GPT-5 vs GPT-5.5 Pro
GPT-5 (2025) and GPT-5.5 Pro (2026) are frontier reasoning models from OpenAI. GPT-5 ships a 128K-token context window, while GPT-5.5 Pro ships a 1M-token context window. On SWE-bench Verified, GPT-5.5 Pro leads by 13.8 pts. On pricing, GPT-5 costs $1.25/1M input tokens versus $30/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
GPT-5 is ~2300% cheaper at $1.25/1M; pay for GPT-5.5 Pro only for coding workflow support.
Specs
| Released | 2025-01-21 | 2026-04-23 |
| Context window | 128K | 1M |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | - | - |
Pricing and availability
| GPT-5 | GPT-5.5 Pro | |
|---|---|---|
| Input price | $1.25/1M tokens | $30/1M tokens |
| Output price | $10/1M tokens | $180/1M tokens |
| Providers |
Capabilities
| GPT-5 | GPT-5.5 Pro | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | GPT-5 | GPT-5.5 Pro |
|---|---|---|
| SWE-bench Verified | 74.9 | 88.7 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has GPT-5 at 74.9 and GPT-5.5 Pro at 88.7, with GPT-5.5 Pro ahead by 13.8 points. The largest visible gap is 13.8 points on SWE-bench Verified, 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 Pro. Both models share vision, multimodal input, function calling, and tool use, 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 lists $1.25/1M input and $10/1M output tokens, while GPT-5.5 Pro lists $30/1M input and $180/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts GPT-5 lower by about $71.13 per million blended tokens. Availability is 2 providers versus 1, so concentration risk also matters.
Choose GPT-5 when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose GPT-5.5 Pro 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-5 or GPT-5.5 Pro?
GPT-5.5 Pro supports 1M tokens, while GPT-5 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-5 or GPT-5.5 Pro?
GPT-5 is cheaper on tracked token pricing. GPT-5 costs $1.25/1M input and $10/1M output tokens. GPT-5.5 Pro costs $30/1M input and $180/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5 or GPT-5.5 Pro open source?
GPT-5 is listed under Proprietary. GPT-5.5 Pro 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 or GPT-5.5 Pro?
Both GPT-5 and GPT-5.5 Pro 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 or GPT-5.5 Pro?
Both GPT-5 and GPT-5.5 Pro 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 and GPT-5.5 Pro?
GPT-5 is available on Replicate API and OpenRouter. GPT-5.5 Pro is available on OpenAI API. Provider coverage can affect latency, region availability, compliance posture, and fallback options. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Continue comparing
Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.