GPT-5.6 Sol vs GPT-5.5
Facts only. This page does not pick a winner. For a picked winner, see the use case comparison on Tools.
| GPT-5.6 Sol | GPT-5.5 | |
|---|---|---|
| API model IDs | gpt-5.6-sol | gpt-5.5, gpt-5.5-2026-04-23 |
| Context window | 1,050,000 | 1,050,000 |
| Lifecycle | active | active |
| License | proprietary | proprietary |
| Trains on API data | No | No |
| Zero data retention | on-request | on-request |
| Input per 1M tokens | $4 (verified 2026-09-08) | $5 (verified 2026-09-08) |
Frequently asked questions
- Which has the larger context window, GPT-5.6 Sol or GPT-5.5?
- GPT-5.6 Sol holds 1,050,000 tokens and GPT-5.5 holds 1,050,000. Both hold 1,050,000 tokens. The context window counts the prompt, any attached files, and the reply together.
- Which is cheaper, GPT-5.6 Sol or GPT-5.5?
- Per million input tokens, GPT-5.6 Sol was $4 (verified 2026-09-08) and GPT-5.5 was $5 (verified 2026-09-08). GPT-5.6 Sol is cheaper per input token. Output tokens cost $20 and $30 respectively, and output volume usually decides the bill.
- Does GPT-5.6 Sol or GPT-5.5 train on API data?
- GPT-5.6 Sol does not train on API data by default, and GPT-5.5 does not train on API data by default. Zero data retention is on-request for GPT-5.6 Sol and on-request for GPT-5.5. Verified 2026-09-08 and 2026-09-08 against the providers' own documentation.
- Is GPT-5.6 Sol or GPT-5.5 being retired?
- GPT-5.6 Sol is active. GPT-5.5 is active. Lifecycle checked 2026-09-08 and 2026-09-08. Pin a dated snapshot ID rather than an alias if a retirement would break you.