Model comparison - Same provider, successor
GPT-5.5 vs GPT-5.6 Sol
GPT-5.5 and GPT-5.6 Sol are both OpenAI models. On list price, GPT-5.6 Sol charges 20% less than GPT-5.5 for input ($4 vs $5 per 1M tokens), and GPT-5.5 charges 1.5x GPT-5.6 Sol's output price ($30 vs $20 per 1M tokens). GPT-5.5 and GPT-5.6 Sol both have a 1,050,000-token context window, and both return up to 128,000 output tokens per response. GPT-5.5 was released on April 24, 2026 and GPT-5.6 Sol on July 9, 2026. Both are closed-weights models, available only through an API.
Last verified from each provider's pricing page. All sources
Side-by-side specs
| Spec | GPT-5.5 | GPT-5.6 Sol |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Input / 1M tokens | $5 | $4 |
| Output / 1M tokens | $30 | $20 |
| Cache read / 1M | $0.50 | $0.40 |
| Cache write / 1M | - | $5 |
| Batch input / 1M | $2.50 | $2 |
| Batch output / 1M | $15 | $10 |
| Long-context rates above | 272,000 tokens | 272,000 tokens |
| Context window | 1,050,000 | 1,050,000 |
| Max output | 128,000 | 128,000 |
| Release date | ||
| Weights | Closed | Closed |
| API model id | gpt-5.5 | gpt-5.6-sol |
| AI Gateway id | openai/gpt-5.5 | openai/gpt-5.6-sol |
| Last verified |
Prices in USD per 1M tokens at each provider's standard first-party rate. A dash means the provider does not bill that item separately or no primary page states it.
What each costs in practice
The same three workloads every model page uses, worked from each model's standard list rates. Swap in your own token counts with the math on each model's page.
| Workload | GPT-5.5 | GPT-5.6 Sol |
|---|---|---|
| One agent session1M input tokens and 100K output tokens, no caching. | $8.00 | $6.00 |
| A chat app10,000 requests a day at 2K input and 500 output tokens each. | $250.00$7,500.00 per 30-day month | $180.00$5,400.00 per 30-day month |
| The same session at a 90% cache hit90% of the input is read from the prompt cache. The one-time cache write premium is not included. | $3.95 | $2.76 |
Show the math
GPT-5.5
- One agent sessionInput: 1M x $5 = $5.00Output: 0.1M x $30 = $3.00
- A chat appInput: 20M x $5 = $100.00Output: 5M x $30 = $150.00
- The same session at a 90% cache hitCached input: 0.9M x $0.50 = $0.45Uncached input: 0.1M x $5 = $0.50Output: 0.1M x $30 = $3.00
GPT-5.6 Sol
- One agent sessionInput: 1M x $4 = $4.00Output: 0.1M x $20 = $2.00
- A chat appInput: 20M x $4 = $80.00Output: 5M x $20 = $100.00
- The same session at a 90% cache hitCached input: 0.9M x $0.40 = $0.36Uncached input: 0.1M x $4 = $0.40Output: 0.1M x $20 = $2.00
Benchmarks under the same setting
Only boards that list both models under the same run setting appear here, one row per board and setting, with each score exactly as the board shows it. Scores on different boards use different scales and are never combined.
| Board and setting | GPT-5.5 | GPT-5.6 Sol |
|---|---|---|
| tau3-Banking (tau-knowledge)tau3-Banking leaderboard, banking_knowledge pass^1; standard submission by Sierra; reasoning effort: xhigh; retrieval config: alltools; user simulator gpt-5.2Official leaderboard - taubench.com | 44.6% | 46.9% |
Set them up in your tools
Step-by-step guides whose official docs list GPT-5.5 or GPT-5.6 Sol by model id.
Model pages
FAQ
How do GPT-5.5 and GPT-5.6 Sol compare on price?
On list price, GPT-5.6 Sol charges 20% less than GPT-5.5 for input ($4 vs $5 per 1M tokens), and GPT-5.5 charges 1.5x GPT-5.6 Sol's output price ($30 vs $20 per 1M tokens). For one agent session of 1M input and 100K output tokens with no caching, that is $8.00 on GPT-5.5 and $6.00 on GPT-5.6 Sol. Prices are each provider's first-party list rates, verified October 17, 2026 and October 17, 2026.
What are the context windows of GPT-5.5 and GPT-5.6 Sol?
GPT-5.5 and GPT-5.6 Sol both have a 1,050,000-token context window, and both return up to 128,000 output tokens per response.
Are GPT-5.5 and GPT-5.6 Sol open weights?
GPT-5.5 is closed-weights and is called through OpenAI's API as gpt-5.5. GPT-5.6 Sol is closed-weights and is called through OpenAI's API as gpt-5.6-sol.
More comparisons
Sources
GPT-5.5 verified from developers.openai.com; GPT-5.6 Sol verified from developers.openai.com. This page is as current as the older of the two: .
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