As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/m/gpt-6-astra/

# GPT-6 Astra

OpenAI, GPT-6 family. Status: current. Type: reasoning model. Released: 2026-09-03. Training cutoff: 2026-04.

## How to call it

| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| OpenAI API | `gpt-6-astra` | https://api.openai.com/v1/responses | https://developers.openai.com/api/docs/models/gpt-6-astra |
| Azure OpenAI (Microsoft Foundry) | `gpt-6-astra` |  | https://learn.microsoft.com/en-us/azure/foundry/foundry-models/concepts/models-sold-directly-by-azure |
| OpenRouter | `openai/gpt-6-astra` |  | https://openrouter.ai/openai/gpt-6-astra |
| Web app |  |  | https://chatgpt.com |

## Pricing

- Input: $10 per 1M tokens
- Cached input: $1 per 1M tokens
- Output: $50 per 1M tokens
- Cache write: $12.50 per 1M tokens
- Unit as published: per 1M tokens (USD), standard tier
- Note: prompts >272K input tokens billed at 2x input and cache rates
- Source: https://developers.openai.com/api/docs/pricing
- Last checked: 2026-09-29

## Specs

- Input: text, image
- Output: text
- Context window: 1,050,000 tokens
- Max output: 128,000 tokens
- Open weights: no
- Licence: proprietary

## What it has not seen

- Published training cutoff: 2026-04 (April 2026).
- AI events after it on Post-Cutoff: 1,863 (426 major, 83 historic), as of 2026-11-13.
- Already missing at launch: 271.
- Briefings of the news since April 2026: https://postcutoff.com/briefings/cutoff-2026-04-s.md (short), https://postcutoff.com/briefings/cutoff-2026-04-m.md (medium), https://postcutoff.com/briefings/cutoff-2026-04.md (full).
- Its card, with five things it has never heard of: https://postcutoff.com/you/gpt-6-astra/

## What stands out

- Max reasoning effort: reasoning.effort adds a new "max" level above xhigh (low/medium/high/xhigh/max). Source: https://developers.openai.com/api/docs/models/gpt-6-astra
- 1M-token context: 1.05M context window (922K max input) with 128K output on the flagship. Source: https://developers.openai.com/api/docs/models/gpt-6-astra
- Restricted cyber behaviour: Released as a restricted version that rejects certain cybersecurity prompts; separate Cyber/Daybreak models exist for that domain. Source: https://en.wikipedia.org/wiki/GPT-6_Astra
- Recurrent-depth reasoning (found after launch): Reported new "recurrent depth" technique that obscures some of the reasoning, raising monitorability concerns among safety researchers. Source: https://en.wikipedia.org/wiki/GPT-6_Astra
- Ultrafast service tier (found after launch): From Sept 29 2026, service_tier "ultrafast" gives up to 6x faster generation in the API (8x / ~300 tok/s in Codex) at 6x price: $60 input / $6 cached / $75 cache write / $300 output per 1M tokens (<=272K ctx); default limits 500K-5M TPM. Source: https://developers.openai.com/api/docs/guides/ultrafast-mode
- Powers dots always-on agents (found after launch): OpenAI's dots (launched Sept 29 2026) run on GPT-6 Astra, each with its own cloud computer; also the default model in Agents API computer-use examples. Source: https://openai.com/index/introducing-dots/

## Notes

OpenAI flagship ("most capable model, built for the hardest end-to-end work"). API changelog: Sep 3 2026 (limited preview Sep 3, public Sep 4). Single snapshot gpt-6-astra. OpenRouter also lists openai/gpt-6-astra-pro = same model with reasoning.mode pro. Endpoints: Chat Completions, Responses, Batch.

Hardest end-to-end work: long-horizon agentic coding, research, analysis, computer use.

```bash
curl https://api.openai.com/v1/responses \
 -H "Authorization: Bearer $OPENAI_API_KEY" -H "Content-Type: application/json" \
 -d '{"model":"gpt-6-astra","input":"Hello"}'
```

Sources:
- https://developers.openai.com/api/docs/models/gpt-6-astra
- https://developers.openai.com/api/docs/pricing
- https://developers.openai.com/api/docs/changelog
- https://en.wikipedia.org/wiki/GPT-6_Astra
- Ultrafast: https://developers.openai.com/api/docs/guides/ultrafast-mode
- Models overview: https://developers.openai.com/api/docs/models

Model page: https://postcutoff.com/m/gpt-6-astra/