Claude Opus 5.5 vs Grok 4.7 vs GPT-6 Astra
Too close to call on our weighted score (Claude Opus 5.5 64, GPT-6 Astra 64, Grok 4.7 61). The right pick depends on what you value most.
AnthropicClaude Opus 5.5
64/100- ECI167.4
- Price$4.00 / $20.00
- Context1M
xAIGrok 4.7
61/100- ECI—
- Price$2.00 / $6.00
- Context500K
OpenAIGPT-6 Astra
64/100- ECI166.5
- Price$10.00 / $50.00
- Context1.05M
Too close to call
It is close. Our weighted score puts them within a point (Claude Opus 5.5 64/100, GPT-6 Astra 64/100, Grok 4.7 61/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and Grok 4.7 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because Grok 4.7 has no Capabilities Index score yet.
- CapabilityGPT-6 AstraShared benchmarks: GPT-6 Astra 91.3% · Claude Opus 5.5 88.5% · Grok 4.7 74.9%
- Lowest priceGrok 4.7Grok 4.7 $3.00 · Claude Opus 5.5 $8.00 · GPT-6 Astra $20.00 per 1M tokens (3:1 blend)
- Longest contextGPT-6 AstraGPT-6 Astra 1,050,000 · Claude Opus 5.5 1,000,000 · Grok 4.7 500,000 tokens
- Widest inputsSame inputsClaude Opus 5.5: Text, Images, PDFs · Grok 4.7: Text, Images, PDFs · GPT-6 Astra: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Claude Opus 5.5 | Grok 4.7 | GPT-6 Astra |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 89 | 75 | 91 |
| Price | 25% | 7 | 27 | 0 |
| Inputs & features | 15% | 80 | 80 | 80 |
| Context window | 10% | 60 | 48 | 61 |
| Overall | 100% | 64/100 | 61/100 | 64/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Opus 5.5Anthropic | Grok 4.7xAI | GPT-6 AstraOpenAI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 167.4 (best) | — | 166.5 |
| ECI rank | #1 of 148 (best) | — | #2 of 148 |
| GPQA DiamondGraduate-level science questions | 90.6% | 92.7% | 95.8% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 91.2% | 53.0% | 93.7% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 98.1% | 100% (best) |
| SimpleQA VerifiedShort factual questions | 72.2% | 56.0% | 75.6% (best) |
| Price per million tokens | |||
| Input | $4.00 | $2.00 (best) | $10.00 |
| Output | $20.00 | $6.00 (best) | $50.00 |
| Cached input | $0.20 (best) | $0.50 | $1.00 |
| Blended (3:1) | $8.00 | $3.00 (best) | $20.00 |
| Long-context rate | Same rate | Over 200K: $4.00 / $12.00 | Over 272K: $20.00 / $75.00 |
| Price source | Official Anthropic API | Official xAI API | Official OpenAI API |
| Limits | |||
| Context window | 1,000,000 tokens | 500,000 tokens | 1,050,000 tokens (best) |
| Max output | 128,000 tokens | 500,000 tokens (best) | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · medium · high · xhigh | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | claude-opus-5-5 | grok-4.7 | gpt-6-astra |
| API providers | 28 (best) | 17 | 26 |
| Released | Sep 22, 2026 | Sep 21, 2026 | Sep 4, 2026 |
| Knowledge cutoff | Jun 2026 | May 2026 | Apr 30, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Claude Opus 5.5$80.00
- Grok 4.7$32.00
- GPT-6 Astra$200.00
Which should you choose?
Which is better: Claude Opus 5.5, Grok 4.7 or GPT-6 Astra?
It is close. Our weighted score puts them within a point (Claude Opus 5.5 64/100, GPT-6 Astra 64/100, Grok 4.7 61/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and Grok 4.7 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because Grok 4.7 has no Capabilities Index score yet.
Which is cheaper, Claude Opus 5.5, Grok 4.7 or GPT-6 Astra?
Grok 4.7 is cheaper at $2.00 input / $6.00 output per million tokens (official xAI API price). Claude Opus 5.5 costs $4.00 input / $20.00 output per million tokens (official Anthropic 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 $3.00 per million tokens for Grok 4.7 versus $8.00 for Claude Opus 5.5 (2.7× as much) and $20.00 for GPT-6 Astra (6.7× as much).
Which scores higher on benchmarks?
Not every model here has a Capabilities Index score, so we compare the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified): GPT-6 Astra 91.3%, Claude Opus 5.5 88.5% and Grok 4.7 74.9%. On individual benchmarks: GPQA Diamond — GPT-6 Astra 95.8%, Grok 4.7 92.7%, Claude Opus 5.5 90.6%; FrontierMath Tiers 1–3 — GPT-6 Astra 93.7%, Claude Opus 5.5 91.2%, Grok 4.7 53.0%; OTIS Mock AIME 2024–2025 — Claude Opus 5.5 100%, GPT-6 Astra 100%, Grok 4.7 98.1%; SimpleQA Verified — GPT-6 Astra 75.6%, Claude Opus 5.5 72.2%, Grok 4.7 56.0%.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Opus 5.5, Grok 4.7 and GPT-6 Astra 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. All three support tool calling for agent workflows.
Which has the bigger context window?
GPT-6 Astra has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Opus 5.5 and 500,000 for Grok 4.7. Maximum output per response: Claude Opus 5.5 up to 128,000, Grok 4.7 up to 500,000, GPT-6 Astra up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Claude Opus 5.5 accepts text, images and PDFs; Grok 4.7 accepts text, images and PDFs; GPT-6 Astra accepts text, images and PDFs. They handle the same number of input types.
Are any of these open source?
No. Claude Opus 5.5, Grok 4.7 and GPT-6 Astra are proprietary and only available through APIs and apps.
Which is newer?
Claude Opus 5.5 is the newest, released Sep 22, 2026. Grok 4.7 came out Sep 21, 2026; GPT-6 Astra came out Sep 4, 2026. Knowledge cutoff: Claude Opus 5.5 Jun 2026, Grok 4.7 May 2026, GPT-6 Astra Apr 30, 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.
