GPT-6.1 Sol vs GPT-6 Astra: 5x Price Gap, Benchmarks, Which to Use
Updated 2026-10-08
Short answer: GPT-6 Astra is OpenAI's flagship and still scores a bit higher overall, but GPT-6.1 Sol costs one fifth as much and matches it on several benchmarks. Astra lists at $10 per million input tokens and $50 per million output; GPT-6.1 Sol at $2 and $10. On the six benchmarks reported for both, each model wins three. For most coding-agent and document work, start with 6.1 Sol and escalate only the hardest tasks to Astra.
Both are OpenAI models from September 2026: GPT-6 Astra arrived at the start of the month (September 3–4 depending on the source), and GPT-6.1 Sol was announced at DevDay on September 29. For background on Sol, see what GPT-6.1 Sol is.
GPT-6.1 Sol vs GPT-6 Astra at a glance
| GPT-6.1 Sol | GPT-6 Astra | |
|---|---|---|
| Tier | Cost-effective high-end | Flagship |
| Released | September 29, 2026 | Early September 2026 |
| API price (input / output per 1M) | $2 / $10 | $10 / $50 |
| Cached input per 1M | $0.10 | $1.25 |
| Context window | ~1.05M tokens | ~1.05M tokens |
| Max output | 128K tokens | 128K tokens |
| Knowledge cutoff | April 2026 | April 2026 |
| LLM Stats overall score | 53.9 | 58.3 |
Figures are list prices and tracker data as of October 8, 2026 (LLM Stats, launch coverage). Check OpenAI's pricing page before budgeting.
Benchmarks: where each one wins
On LLM Stats, six benchmarks have results for both models, and they split evenly:
- GPT-6 Astra leads: FrontierCode 1.1 (full-repository coding), OSWorld 2.0 (computer use) and Terminal-Bench Science 0.1.
- GPT-6.1 Sol leads: DeepSWE 1.1 (software engineering, 75.2% for Sol), FrontierMath Tier 4 v2 and HealthBench Professional.
On the tracker's category indexes Astra is ahead on reasoning, coding, agents and especially tool use, which fits its role as the model for long, end-to-end jobs. Astra's own launch numbers are strongest on formal problems – for example 97.6% on FrontierMath Tier 4 and 99.9% on ARC-AGI-3 as reported at launch.
Treat any single score with care: vendors report many of these themselves and harness settings differ. A 20–50 task test on your own work beats any leaderboard.
Price: what a 5x gap means per task
Take a coding task that reads 200,000 tokens and writes 20,000:
- GPT-6.1 Sol: 0.2 × $2 + 0.02 × $10 = $0.60
- GPT-6 Astra: 0.2 × $10 + 0.02 × $50 = $3.00
For the same budget you can run Sol five times. Astra only pays off where it solves something Sol can't – if Sol needs five attempts for a task Astra does once, they cost the same. Repeated context is where caching matters: $0.10 versus $1.25 per million cached tokens.
Which should you use?
Choose GPT-6.1 Sol if:
- You run coding agents or document pipelines at volume and cost per task matters.
- You work in Codex, where 6.1 Sol is the default model, or in ChatGPT Work.
- Your tasks are well-specified: bug fixes, refactors, extraction, summaries.
Choose GPT-6 Astra if:
- The task is long and open-ended and a failure is expensive.
- You need heavy computer use or tool chaining (Astra leads OSWorld 2.0 and the tool-use index).
- You work on formal math, science workflows in the terminal or other closed-world problems where Astra's launch results stand out.
Route between them: send everything to Sol first, and retry failures or flagged "hard" tickets on Astra. That usually keeps most of Astra's quality at a fraction of its bill. To compare both against Anthropic's top model, see GPT-6.1 vs Claude Opus 5.5 and Opus 5.5 vs GPT-6.
How to test 6.1 Sol vs 6 Astra yourself
- Collect 20–50 real tasks from your backlog, not toy prompts.
- Run both models with the same prompt, tools and effort setting.
- Record pass/fail, tokens, wall-clock time.
- Compute cost per solved task – the only number that matters for budgeting.
- Re-test after point releases; OpenAI ships them often.
FAQ
Is GPT-6.1 Sol better than GPT-6 Astra?
Not overall – Astra has the higher composite score (58.3 vs 53.9 on LLM Stats). But the two split their shared benchmarks 3–3, and Sol costs 5x less, so for many coding tasks Sol is the better value.
How much cheaper is 6.1 Sol than 6 Astra?
Five times on standard API prices: $2/$10 per million input/output tokens versus $10/$50.
Do GPT-6.1 Sol and GPT-6 Astra have the same context window?
Yes, about 1.05 million input tokens and up to 128K output tokens each.
What is the difference between GPT-6 Sol and GPT-6.1 Sol?
GPT-6.1 Sol is the September 29 update of GPT-6 Sol, positioned closer to Astra on coding and agent work at the same $2/$10 price. See GPT-6 Sol vs GPT-5.6 Sol for the earlier step.
Which model does Codex use?
At DevDay OpenAI made GPT-6.1 Sol the default model in Codex.