GPT-5.5 Pro
OpenAI released 2026-04-24 proprietary
No independent quality score.
No benchmark we track has measured this model. That is not the same as measuring it and finding it wanting — we simply cannot rank it, so we do not.
Our take
editorial — not a measurementAt $30/$180 short-context and $60/$270 long, this is the most expensive model in the dataset by a wide margin, and OpenAI publishes no cached-input rate for it — so the single biggest cost lever on long agentic runs is simply unavailable. It sits in the same bracket as GPT-5.4 Pro at identical pricing. Justifying it requires evidence that it beats Opus 5 at $5/$25 by enough to cover a 6x input and 7x output premium, and no published benchmark in this pass shows that. Reach for it only for one-shot, very high-stakes reasoning where cost is genuinely irrelevant.
Strengths
- Top-end OpenAI reasoning capability
- 1.05M context window, 128k output
- 50% batch discount still applies
Weaknesses
- $30/$180 — the most expensive model here
- No cached-input pricing published, removing the main cost lever
- Long-context tier escalates to $60/$270
- No benchmark evidence captured that justifies the premium over Opus 5
Reach for it when
- One-shot high-stakes reasoning
- Cases where a human expert hour is the alternative
Avoid it if
- Anything with repeated context — you cannot cache it
- Cost matters at all
- Volume workloads
Sources: developers.openai.comarena.ai
Every price dimension
| Input | $30.00/M |
|---|---|
| Output | $180/M |
| Web search | $0.01/call |
| Batch discount | 50% |
Past 272,000 tokens the price changes. Input goes to $60.00/M (2×) and output to $270/M. The headline rate does not apply to a long-context workload.
Independent scores
No independent benchmark has measured this model.
Capability
| Context window | 1.1M |
|---|---|
| Max output | 128K |
| Input modes | file, image, text |
| Tool use | yes |
| Reasoning | always on |
| Knowledge cutoff | 2025-12-01 |
| Open weights | no |
Provenance
| Price source | openrouter.ai |
|---|---|
| Fetched | 2026-08-24 |
| Quality data | unrated |
| Cross-checked | vendor page |
GPT-5.5 Pro is OpenAI’s high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1M+ token context window (922K input, 128K output) with support for...