Claude Opus 5.5 vs GPT-6 Astra
There is no quality verdict yet: the AIGROW small-business benchmark has not run Claude Opus 5.5. On price, Claude Opus 5.5 costs less: $4 in and $20 out per million tokens, against $10 in and $50 out for GPT-6 Astra.
US dollars, standard rate, shortest context band. Price only: the benchmark has not run both.
- Claude Opus 5.5
- $20.00
- GPT-6 Astra
- $50.00
- Claude Opus 5.5, per M tokens
- $4 / $20
- GPT-6 Astra, per M tokens
- $10 / $50
3,000 tokens in and 400 out each, at list price.
The flagships Anthropic and OpenAI point new work to, with Opus at less than half the Astra price. 1,000 support replies cost $50.00 on GPT-6 Astra and $20.00 on Claude Opus 5.5, so GPT-6 Astra costs 2.5 times as much.
What each one costs
The API price per million tokens and the cheapest app plan with each model, from the makers’ own pages. Each name opens that model’s full price page.
- Claude Opus 5.5
- On the Anthropic API, Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens. In Claude, the cheapest plan with it is Pro at $20/mo. Plan prices read 20 October 2026. AIGROW API credit runs Claude Opus 5.5 at $1.00 / $5.00 per million input / output tokens, up to 75% below list price. See API credit
- GPT-6 Astra
- On the OpenAI API, GPT-6 Astra costs $10 per million input tokens and $50 per million output tokens. In ChatGPT, the cheapest plan with it is Plus at $20/mo. Plan prices read 14 October 2026. AIGROW API credit runs GPT-6 Astra at $2.50 / $12.50 per million input / output tokens, 75% below list price. See API credit
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 | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Tier | Flagships | Flagships |
| Input, per M tokens | $4.00 | $10.00 |
| Output, per M tokens | $20.00 | $50.00 |
| Cached input | $0.20 | $1.00 |
| Context window | 1M | 1.05M |
| Released | 22 Sep 2026 | 3 Sep 2026 |
| Weights | Closed weights | Closed weights |
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 | Claude Opus 5.5 | GPT-6 Astra | Cheaper |
|---|---|---|---|
| Support reply3,000 in, 400 out. | $20.00 | $50.00 | Claude Opus 5.5, 60% less |
| Document summary25,000 in, 1,000 out. | $120 | $300 | Claude Opus 5.5, 60% less |
| Agent task80,000 in (70,000 cached), 3,000 out. | $114 | $320 | Claude Opus 5.5, 64% 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.
- Claude Opus 5.5
- Cache read is 0.05x input on this model ($0.20). Cache write $5 (5 min) or $8 (1 h). Fast mode $8 / $40. Batch API 50% off. US-only inference bills 1.1x. Full context window billed at standard rates. Max output 128K. Anthropic’s pricing page
- GPT-6 Astra
- Requests above 272K input tokens bill 2x input and 1.5x output ($20 / $75, cached $2). Cache write $12.50. Batch and Flex 50% off, Fast mode 2x, Ultrafast mode $60 / $300 since 29 September 2026. Data residency adds 10%. Context 1,050,000 with max input 922K. OpenAI’s pricing page
Other comparisons
Every head to head on the list that involves Claude Opus 5.5 or GPT-6 Astra.
Run both up to 75% below list price
AIGROW API credit covers Claude Opus 5.5 and GPT-6 Astra at published rates never above the list prices here, and $25 buys $100 of credit.
Prices checked 15 October 2026