GPT-6 Astra vs GPT-5.6 Sol
Too close to call on our weighted score (GPT-6 Astra 68, GPT-5.6 Sol 66). The right pick depends on what you value most.
OpenAIGPT-6 Astra
68/100- ECI166.5
- Price$10.00 / $50.00
- Context1.05M
- OpenAI
GPT-5.6 Sol
66/100- ECI161.8
- Price$4.00 / $20.00
- Context1.05M
Add a model
Make it a three-way comparison.
Too close to call
It is close. Our weighted score puts them within 1 points (GPT-6 Astra 68/100, GPT-5.6 Sol 66/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and GPT-5.6 Sol on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-6 AstraCapabilities Index (ECI): GPT-6 Astra 166.5 · GPT-5.6 Sol 161.8
- Lowest priceGPT-5.6 SolGPT-5.6 Sol $8.00 · GPT-6 Astra $20.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGPT-6 Astra 1,050,000 · GPT-5.6 Sol 1,050,000 tokens
- Widest inputsSame inputsGPT-6 Astra: Text, Images, PDFs · GPT-5.6 Sol: Text, Images, PDFs
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | GPT-6 Astra | GPT-5.6 Sol |
|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 99 | 93 |
| Price | 25% | 0 | 7 |
| Inputs & features | 15% | 80 | 80 |
| Context window | 10% | 61 | 61 |
| Overall | 100% | 68/100 | 66/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-6 AstraOpenAI | GPT-5.6 SolOpenAI |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | 166.5 (best) | 161.8 |
| ECI rank | #2 of 148 (best) | #8 of 148 |
| GPQA DiamondGraduate-level science questions | 95.8% (best) | 93.5% |
| FrontierMath Tiers 1–3Research-level mathematics | 93.7% (best) | 89.1% |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% | 100% |
| SimpleQA VerifiedShort factual questions | 75.6% (best) | 69.7% |
| Price per million tokens | ||
| Input | $10.00 | $4.00 (best) |
| Output | $50.00 | $20.00 (best) |
| Cached input | $1.00 | $0.40 (best) |
| Blended (3:1) | $20.00 | $8.00 (best) |
| Long-context rate | Over 272K: $20.00 / $75.00 | Over 272K: $8.00 / $30.00 |
| Price source | Official OpenAI API | Official OpenAI API |
| Limits | ||
| Context window | 1,050,000 tokens | 1,050,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | Yes | Yes |
| Audio | No | No |
| Video | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes |
| Structured output | Yes | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | gpt-6-astra | gpt-5.6-sol |
| API providers | 26 | 40 (best) |
| Released | Sep 4, 2026 | Jul 9, 2026 |
| Knowledge cutoff | Apr 30, 2026 | Feb 16, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-6 Astra$200.00
- GPT-5.6 Sol$80.00
Which should you choose?
Which is better: GPT-6 Astra or GPT-5.6 Sol?
It is close. Our weighted score puts them within 1 points (GPT-6 Astra 68/100, GPT-5.6 Sol 66/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and GPT-5.6 Sol on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-6 Astra or GPT-5.6 Sol?
GPT-5.6 Sol is cheaper at $4.00 input / $20.00 output per million tokens (official OpenAI API price). GPT-6 Astra costs $10.00 input / $50.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $8.00 per million tokens for GPT-5.6 Sol versus $20.00 for GPT-6 Astra (2.5× as much).
Which scores higher on benchmarks?
GPT-6 Astra scores higher on the Capabilities Index (ECI): GPT-6 Astra 166.5 (#2 of 148) and GPT-5.6 Sol 161.8 (#8 of 148). The confidence ranges of the top two overlap (163.1–171.1 vs 159.3–165.3), so treat the gap as small. On individual benchmarks: GPQA Diamond — GPT-6 Astra 95.8%, GPT-5.6 Sol 93.5%; FrontierMath Tiers 1–3 — GPT-6 Astra 93.7%, GPT-5.6 Sol 89.1%; OTIS Mock AIME 2024–2025 — GPT-6 Astra 100%, GPT-5.6 Sol 100%; SimpleQA Verified — GPT-6 Astra 75.6%, GPT-5.6 Sol 69.7%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6 Astra and GPT-5.6 Sol yet, so there is no like-for-like coding score. On overall capability, GPT-6 Astra leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.
Which has the bigger context window?
GPT-6 Astra and GPT-5.6 Sol share the same 1,050,000-token context window. Maximum output per response: GPT-6 Astra up to 128,000, GPT-5.6 Sol up to 128,000 tokens.
Which can read images, PDFs, audio or video?
GPT-6 Astra accepts text, images and PDFs; GPT-5.6 Sol accepts text, images and PDFs. They handle the same number of input types.
Are any of these open source?
No. GPT-6 Astra and GPT-5.6 Sol are proprietary and only available through APIs and apps.
Which is newer?
GPT-6 Astra is the newest, released Sep 4, 2026. GPT-5.6 Sol came out Jul 9, 2026. Knowledge cutoff: GPT-6 Astra Apr 30, 2026, GPT-5.6 Sol Feb 16, 2026.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
