About GPT-5.6 Sol
GPT-5.6 Sol is the frontier tier of OpenAI's GPT-5.6 family, described by OpenAI as its model for complex professional work — the tier the plain gpt-5.6 alias points to. It accepts text and images and replies in text, with reasoning effort adjustable from none for quick answers up to max for the hardest problems.
The family's context window is in the million-token class, large enough to hold entire codebases or document sets in one request. Within the family, Sol corresponds to the unsuffixed flagship tier of earlier GPT-5 generations, with Terra and Luna filling the tiers below it.
Sol carries the family's premium price: its output rate is several times its input rate, so response length drives spend more than prompt size does. Prompt caching cuts the input rate by an order of magnitude for repeated prefixes, and the savings scale with the price — caching matters more at this tier than any other. Two caveats worth pricing in: prompts past OpenAI's long-context threshold are billed at a multiplier for the entire request, and batch processing is available when a turnaround window is acceptable. For work that doesn't need frontier reasoning, Terra offers the same context and features at a fraction of the rate. OpenAI labels Sol's standard rate as promotional with a stated end date, so the callout above is the thing to re-check when budgeting past it.
Frequently asked questions
How much does the GPT-5.6 Sol API cost?
GPT-5.6 Sol costs $4 per million input tokens and $20 per million output tokens, with cached input at $0.4 per million (90% off). Note: Promotional rate OpenAI states is available at least through 21 Nov 2026 (a 20% input / 33% output cut from the prior $5 / $30 list). Prompts over 272K input tokens are billed at 2× input and 1.5× output for the whole request.
How much does a typical chat message cost with GPT-5.6 Sol?
A short chat message (about 500 input and 250 output tokens) costs roughly $0.0070 with GPT-5.6 Sol. At 1,000 such requests a day, that is about $210.00 per month.
Is GPT-5.6 Sol cheap compared to similar models?
GPT-5.6 Sol has the #25 cheapest input rate of the 29 models we track. On a mixed workload (10K input / 2K output), it costs $0.080 per request, versus $0.044 for Gemini 3.1 Pro Preview and $0.100 for Claude Opus 5.
What does GPT-5.6 Sol cost per 1,000 tokens?
Per 1,000 tokens, GPT-5.6 Sol costs $0.0040 for input and $0.0200 for output, or $0.00040 for cached input. Providers quote rates per million tokens ($4/M in, $20/M out here), so divide by a thousand for the per-1K figure older pricing pages used.
How large a prompt can GPT-5.6 Sol take?
GPT-5.6 Sol accepts up to 1025K tokens of input context and can generate up to 125K tokens of output per request. At its input rate, filling the entire 1025K-token window costs about $4.20 per request before any output.
Related
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All OpenAI model costs: GPT-5.6 Terra · GPT-5.6 Luna · GPT-5.4 · GPT-5 · GPT-5 mini · GPT-5 nano · GPT-4o · GPT-4o mini · o3 · o4-mini
Last updated 2026-09-03. Prices verified against OpenAI's official pricing page; see the methodology.