Model comparison
GPT-5.5 Pro and GPT-6 Astra compared on price, context window, capabilities and published benchmarks. Data comes from the OpenModels registry.
| Specification | GPT-5.5 Pro | GPT-6 Astra |
|---|---|---|
| Developer | Openai | Openai |
| Released | Mar 1, 2026 | Sep 3, 2026 |
| Context window | 256K tokens | 1.05M tokens |
| Input price / 1M | $30.00via OpenAI | $10.00via OpenAI |
| Output price / 1M | $120.00via OpenAI | $50.00via OpenAI |
| Providers | 1 | 1 |
| License | proprietary | proprietary |
| Input modalities | audio, code, image, text | code, image, text |
| Capabilities | chat, completion, function-calling, vision, audio, code-generation, reasoning | chat, completion, function-calling, vision, code-generation, reasoning |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
Only benchmarks with a published score for at least one of the two models are shown. Published scores with their sources. Vendor-reported results use the vendor's own evaluation settings and are not directly comparable across vendors.
| Benchmark | GPT-5.5 Pro | GPT-6 Astra |
|---|---|---|
| Artificial Analysis Intelligence Index | — | 53Artificial Analysis · Independent |