First: where can you use each model?
The September 22, 2026 announcement describes GPT-6 Sol for Work, Codex and the API, with a gradual rollout. That does not make it a universal selector in every chat account. GPT-5.6 Sol has a different history across Chat, Work/Codex and API. Check the product, country and account before promising access.
| Question | GPT-5.6 Sol | GPT-6 Sol | Practical reading |
|---|---|---|---|
| Standard API input per million | $4 promotional rate in the checked sheet | $2 | A published rate is not the cost of a complete task. |
| Standard API output per million | $20 promotional rate | $10 | Long outputs can dominate a bill. |
| Cached input per million | $0.40 | $0.20 | Only applies when the workflow qualifies for caching. |
| Maximum context | 1,050,000 tokens | 1,050,000 tokens | More context does not guarantee correct answers. |
| Maximum output | 128,000 tokens | 128,000 tokens | It does not mean every response reaches that size. |
| Published knowledge cutoff | February 16, 2026 | April 20, 2026 | A later cutoff does not replace checking current facts. |
| Reasoning effort | none, low, medium, high, xhigh and max | none, low, medium, high, xhigh and max | The published effort list is the same. |
| API image input | Supported; no direct image output | Supported; no direct image output | Multimodal input is not image generation. |
| Direct API audio and video | Not supported on the model page | Not supported on the model page | An app may add separate tools; that is a different comparison. |
| Input beyond 272,000 tokens | 2× input price for the whole request | 2× input and cache price for the whole request | Very long contexts need a separate cost estimate. |
A token is a fragment of processed text; it is not a fixed synonym for a word. An application can provide tools or image features even when a model’s direct API modalities differ. Keep the model name separate from ChatGPT subscription plans.
What changes for writing and work
OpenAI presents improvements in factuality and workflows. Those are provider claims, not an independent test. To decide, use a recurring task, fixed review criteria and human checking. Compare format, citations, instruction following and correction time, not a single impressive answer.
If a 5.6 workflow is stable, switching it wholesale adds format, limit and integration risk. Start with a copy or a low-impact task. If the new output needs more correction, a lower token rate may disappear in review time.
API users: token rates versus task cost
In a hypothetical example with 1,000,000 uncached input tokens and 100,000 output tokens, the published Standard rates produce $6 with promotional 5.6 pricing (4 + 2) and $3 with GPT-6 Sol (2 + 1). This is an illustration, not an invoice or guaranteed saving. Tools, reasoning, cache, volume and inputs above 272,000 tokens can change the result.
These are dollar API rates. They are not the price of Plus, Pro or a Work account in the US. Compare actual usage, quotas and billing model before moving an automation.
When to keep a 5.6 workflow
Keep 5.6 when integrations are delicate, output format is stable or a team already reviews its results. Test GPT-6 Sol when access is confirmed and a concrete quality or cost change justifies migration. Do not describe the older model as retired without an official notice.
Which model fits your use?
For API automation with measurable usage, GPT-6 Sol is worth a controlled trial. For Work or Codex, check what your account can access. For ordinary chat, do not infer availability from the API page. GPT-6 Sol is not Astra or Luna; those are different tiers in the consulted sources. See the editorial method and measure one representative workflow first.
Short answer
GPT-6 Sol publishes lower API rates and the same listed context as 5.6 Sol, but access depends on the product. The 50% reduction in the example does not guarantee half the cost for every task. This guide uses official documents checked September 28, 2026; it contains no private benchmark or invented subscription price.