GPT-6 Astra cost model
Updated September 23, 2026 · first published September 23, 2026
GPT-6 Astra is the top model in OpenAI's GPT-6 family. It launched on 3 September 2026, three weeks before GPT-6 Sol and Luna. It costs 5× GPT-6 Sol per token, and on public benchmarks most of its effort settings cost more than a competitor that scores higher.
GPT-6 Astra prices
| Tier | Input | Cached input | Output |
|---|---|---|---|
| Standard | $10.00 | $1.00 | $50.00 |
| Batch or flex | $5.00 | $0.50 | $25.00 |
| Fast mode | $20.00 | $2.00 | $100.00 |
| Long context (over 272K input) | $20.00 | $2.00 | $75.00 |
Per 1M tokens, from OpenAI's pricing page. A cache write costs $12.50. Astra has a 1,050,000-token context window, 128,000 max output tokens and an April 2026 knowledge cutoff.
Astra always reasons. Unlike Sol and Luna it has no none effort setting; the choices are low, medium, high, xhigh and max.
Against other premium models
| Model | Input | Cached | Output |
|---|---|---|---|
| GPT-6 Astra | $10.00 | $1.00 | $50.00 |
| Claude Fable 5.1 | $10.00 | $0.25 | $50.00 |
| Claude Opus 5.5 | $4.00 | $0.20 | $20.00 |
| GPT-6 Sol | $2.00 | $0.20 | $10.00 |
Astra and Claude Fable 5.1 have the same list price, but Fable 5.1 charges a quarter as much for cached input. On a cache-heavy agent that difference is most of the input bill.
Cost per task at each effort level
Artificial Analysis Intelligence Index (v4.3.2):
| Effort | Index score | Cost per task |
|---|---|---|
| low | 45.8 | $0.82 |
| medium | 49.6 | $1.54 |
| high | 50.9 | $1.73 |
| xhigh | 52.4 | $2.31 |
| max | 52.7 | $3.26 |
Only Astra at low effort sits on the price-performance frontier. At 45.8 for $0.82, it fills the gap between Sol at xhigh (44.1, $0.53) and Sol at max (47.5, $1.06). It is also frugal: about 4,400 output tokens per task at low, against 27,200 at max.
From medium upward, Claude Opus 5.5 beats it on both axes. Opus 5.5 at medium scores 51.2 for $1.34, higher than Astra at medium or high and cheaper than either. Opus 5.5 at high scores 53.6 for $1.82, higher than Astra at max for 44% less per task. Full cross-model numbers are in real cost per task.
That is a benchmark result, not a verdict on your workload. It does mean Astra above low effort has to earn its place on your own tasks before you pay for it.
What an agent step costs
A step with 200K input tokens, 90% cached, and 20K output tokens costs $1.38 on Astra: 5× GPT-6 Sol ($0.276) and 2.7× Claude Opus 5.5 ($0.516). At the long-context rate the numbers climb fast: the same step at 270K input is $1.51, at 300K it is $2.64.
Fast mode doubles everything
Fast mode (formerly priority processing, renamed 30 July 2026) costs $20 input and $100 output per 1M tokens. Track service_tier on every request. Both "priority" and "fast" select it, so a dashboard filtering on one value will miss spend under the other.
When Astra is worth it
- Start at low effort. It is the only setting that is cost-efficient on public benchmarks.
- Before raising effort, replay the same tasks on Opus 5.5 and Sol at max. Pay for Astra only where it wins on your tasks.
- Send offline evaluation and bulk jobs through batch at $5/$25.
- Keep fast mode behind an explicit allow-list.
Sources: OpenAI GPT-6 Astra model page, OpenAI pricing, Artificial Analysis. Prices read 23 September 2026.
Related
- GPT-6 pricing: Astra, Sol and Luna
- GPT-6 Sol cost model
- GPT-6 Luna cost model
- Claude Fable 5.1 cost model
- Opus 5.5 cost by effort level
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