GPT-5.6 Sol API Pricing: $4.00 / $20.00 per 1M Tokens
The numbers: GPT-5.6 Sol (OpenAI) bills $4.00 per 1M input tokens, $20.00 per 1M output tokens, and $0.40 per 1M cached input tokens, inside a 1.05M context window. On our reference 200-step agent workload that works out to about $5.38 per task.
Frontier model for complex professional work, coding, research, and tool use. Every figure on this page was read directly from OpenAI’s own documentation on September 18, 2026 — not copied from a third-party comparison table. Rates change; the source link and check date below are part of the data.
Verified rates
| Item | Rate | Unit |
|---|---|---|
| Input | $4.00 | per 1M tokens |
| Output | $20.00 | per 1M tokens |
| Cached input (cache read) | $0.40 | per 1M tokens |
| Context window | 1.05M | tokens |
Billing notes: Promotional rate guaranteed at least through November 21, 2026. Prompts over 272K input tokens bill at 2x input and 1.5x output for the whole request. Cache writes bill at 1.25x the uncached input rate.
Source: OpenAI official pricing ↗, checked September 18, 2026.
What a real workload costs on GPT-5.6 Sol
List rates are not bills. These two reference workloads translate the table above into money. The assumptions are visible so you can swap in your own trace — the cost calculator does exactly that.
Scenario A — one 200-step agent task
A coding agent runs 200 steps against a stable 40,000-token prefix (system prompt, tools, repository map). The prefix is written to cache on the first step, re-read on the remaining 199, and each step produces 500 output tokens. For OpenAI, cache writes bill at 1.25x the uncached input rate.
| Component | Calculation | Cost |
|---|---|---|
| Cache write (once) | 40,000 tokens × $5.00 / 1M | $0.20 |
| Cache reads | 199 × 40,000 × $0.40 / 1M | $3.18 |
| Output | 200 × 500 × $20.00 / 1M | $2.00 |
| Total per task | $5.38 |
Scenario B — one heavy month
A production service pushes 50M fresh input tokens, 150M cached input tokens, and 10M output tokens through GPT-5.6 Sol in a month:
| Component | Volume | Cost |
|---|---|---|
| Fresh input | 50M × $4.00 | $200.00 |
| Cached input | 150M × $0.40 | $60.00 |
| Output | 10M × $20.00 | $200.00 |
| Monthly total | $460.00 |
Head-to-head cost comparisons
- Claude Sonnet 5 vs GPT-5.6 Sol — same workload, $2.69 vs $5.38 (2.0x apart).
- Claude Opus 5 vs GPT-5.6 Sol — same workload, $6.73 vs $5.38 (1.3x apart).
Frequently asked questions
How much does GPT-5.6 Sol cost per million tokens?
GPT-5.6 Sol costs $4.00 per 1M input tokens and $20.00 per 1M output tokens, with cached input at $0.40 per 1M. Verified September 18, 2026 against OpenAI's official pricing.
What is the context window of GPT-5.6 Sol?
GPT-5.6 Sol supports a 1.05M token context window, per OpenAI's documentation checked September 18, 2026.
Does GPT-5.6 Sol support prompt caching?
Yes. Cached input tokens bill at $0.40 per 1M instead of the full input rate; cache writes bill at 1.25x the uncached input rate.
When was this GPT-5.6 Sol price last checked?
On September 18, 2026, against OpenAI's own pricing page: https://developers.openai.com/api/docs/models/gpt-5.6-sol