GPT-5.5 vs GPT-5.6 Sol
The previous flagship against its replacement, which is now cheaper on a promotional price. Both list prices from the makers’ own pages, and what three everyday jobs cost on each.
US dollars, standard rate, shortest context band. Price only: this page does not rank quality.
- GPT-5.5
- $27.00
- GPT-5.6 Sol
- $20.00
- GPT-5.5, per M tokens
- $5 / $30
- GPT-5.6 Sol, per M tokens
- $4 / $20
3,000 tokens in and 400 out each, at list price.
Per million tokens, GPT-5.5 costs $5 in and $30 out; GPT-5.6 Sol costs $4 in and $20 out. 1,000 support replies cost $27.00 on GPT-5.5 and $20.00 on GPT-5.6 Sol, so GPT-5.5 costs 35% more. Both read up to 1.05M tokens at once.
Side by side
Each maker’s published rate for its standard tier. Cached input is what a repeated prompt prefix costs once the provider has stored it.
| Fact | GPT-5.5 | GPT-5.6 Sol |
|---|---|---|
| Maker | OpenAI | OpenAI |
| Tier | Flagships | Flagships |
| Input, per M tokens | $5.00 | $4.00 |
| Output, per M tokens | $30.00 | $20.00 |
| Cached input | $0.50 | $0.40 |
| Context window | 1.05M | 1.05M |
| Released | 24 Apr 2026 | 9 Jul 2026 |
| Weights | Closed | Closed |
What a job costs on each
1,000 runs of each job at the two list prices. The gap moves from job to job because the models price input, output and cached context differently.
| Job | GPT-5.5 | GPT-5.6 Sol | Cheaper |
|---|---|---|---|
| Support reply3,000 in, 400 out. | $27.00 | $20.00 | GPT-5.6 Sol, 26% less |
| Document summary25,000 in, 1,000 out. | $155 | $120 | GPT-5.6 Sol, 23% less |
| Agent task80,000 in (70,000 cached), 3,000 out. | $175 | $128 | GPT-5.6 Sol, 27% less |
The token counts are ours, chosen to look like real work; the prices are the makers’. A model with no published cache price bills the agent task’s repeated context at its full input rate.
The small print
What each base rate leaves out, from the makers’ own pages: surcharges, discounts, promotions and cache pricing.
- GPT-5.5
- Previous flagship. Requests above 272K input tokens bill 2x input and 1.5x output ($10 / $45). Cached price applies only with extended prompt caching. Batch and Flex 50% off. Data residency adds 10%. OpenAI’s pricing page
- GPT-5.6 Sol
- Promotional price since 2026-08-21, 'at least through November 21, 2026'; the previous price was $5 / $30. Requests above 272K input tokens bill 2x input and 1.5x output ($8 / $30). Cache write $5. Batch and Flex 50% off. Data residency adds 10%. OpenAI’s pricing page
Other comparisons
Every head to head on the list that involves GPT-5.5 or GPT-5.6 Sol.
Run both for a quarter of list price
AIGROW API credit covers GPT-5.5 and GPT-5.6 Sol and is metered at the list prices above: $25 buys $100 of usage.
Prices checked 22 September 2026