GPT-5.6 Sol
GPT-5.6 flagship; the gpt-5.6 alias routes here. Superseded by GPT-6 Sol/Astra but still offered. OpenRouter lists $2/$10, lower than OpenAI list price $4/$20.
- Context window
- 1,050,000 tokens
- Max output
- 128,000 tokens
- Knowledge cutoff
- 2026-02
- Input
- text, image
- Output
- text
- License
- proprietary
- Pricing
- input: $4 · cached input: $0.4 · output: $20 · unit note: prompts >272K input tokens billed 2x input / 1.5x output (per 1M tokens (USD), standard tier) source
- Verified
- 2026-09-29
How to call it
| Provider | Model id | Endpoint / URL | Docs |
|---|---|---|---|
| OpenAI API | gpt-5.6-sol | https://api.openai.com/v1/responses | docs |
| Azure OpenAI (Microsoft Foundry) | gpt-5.6-sol | — | docs |
| OpenRouter | openai/gpt-5.6-sol | openrouter.ai/openai/gpt-5.6-sol | — |
| Web app | — | chatgpt.com | — |
Notable capabilities (3)
- Named-tier family: GPT-5.6 introduced the Sol/Terra/Luna tier names (flagship/balanced/fast) replacing pro/mini/nano naming. source
- Max reasoning effort: Reasoning effort none/low/medium/high/xhigh/max. source
- Fast mode long context (found after launch): Fast mode extended to long-context requests on Aug 5 2026. source
Previous flagship; replacement target for deprecated gpt-5/o3 snapshots.
curl https://api.openai.com/v1/responses \
-H "Authorization: Bearer $OPENAI_API_KEY" -H "Content-Type: application/json" \
-d '{"model":"gpt-5.6-sol","input":"Hello"}'
Sources:
Other OpenAI models
GPT-6 Luna · GPT-6 Sol · GPT Image 2.5 Flare · GPT Image 2.5 Sunburst · GPT-6 Astra · GPT-Live-Transcribe · GPT-Transcribe · GPT-5.6 Terra · GPT-Live 1 · GPT-Realtime-2.1 · GPT-Realtime-2 · GPT-Realtime-Translate · GPT-Rosalind · GPT-Audio-1.5 (and gpt-audio / gpt-audio-mini) · GPT-5.3-Codex · gpt-oss-120b · gpt-oss-20b · GPT-4o mini TTS · text-embedding-3-large · text-embedding-3-small · GPT-5.6 Luna · GPT-Realtime-Whisper · GPT-5.5 Pro · GPT-5.5 · GPT Image 2 · GPT-5.4 · GPT-Realtime-1.5 · GPT-4.1 · GPT-4o · TTS-1 / TTS-1 HD · Whisper large-v3 / large-v3-turbo (open weights) · GPT-Realtime and GPT-Realtime mini · o3 · GPT-4o Transcribe / Mini Transcribe / Transcribe Diarize · Whisper (whisper-1 API) · Sora 2