Claude Sonnet 4.5 vs GPT-6 Astra
Claude Sonnet 4.5 (Anthropic) and GPT-6 Astra (OpenAI) compared on benchmarks, pricing, context window, and use-case rankings.
- GPT-6 Astra leads on overall intelligence (ECI 169 vs 147).
- Claude Sonnet 4.5 is cheaper on input tokens — $3.00 vs $10.00 per 1M.
- GPT-6 Astra has a larger context window (1.1M vs 1M tokens).
- GPT-6 Astra ranks higher for coding (95th vs 26th percentile).
| Attribute | Claude Sonnet 4.5 | GPT-6 Astra |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | 147 | 169 |
| Coding | 26 | 95 |
| Math | 41 | 96 |
| Reasoning & Knowledge | 23 | 99 |
| Agentic & Tools | 17 | 96 |
| Specifications | ||
| Developer | Anthropic | OpenAI |
| Family | Claude | GPT |
| Released | Sep 29, 2025 | Sep 3, 2026 |
| Parameters | — | — |
| Availability | API access | API access |
| Context window | 1M | 1.1M |
| Price — $/M input | $3.00 | $10.00 |
| Price — $/M output | $15.00 | $50.00 |
| Inputs | text, image, file | file, image, text |
| Outputs | text | text |
| Benchmarks | ||
| AIME 2024/2025 | 78% | 100% |
| ARC-AGI | 64% | 99% |
| ARC-AGI-2 | 14% | 95% |
| FrontierMath | 15% | — |
| FrontierMath Tier 4 | 4% | — |
| GDPval (win/tie rate) | 50% | — |
| GPQA Diamond | 82% | 96% |
| GSO (code optimization) | 15% | — |
| Humanity's Last Exam | 14% | 55% |
| MATH Level 5 | 98% | — |
| METR task horizon | 2.0 h | — |
| SimpleBench | 54% | — |
| SimpleQA Verified | 31% | 76% |
| SWE-bench Verified | 71% | — |
| Terminal-Bench | 47% | — |
| WebDev Arena | 1391 | 1797 |
| WeirdML | 48% | 93% |
| APEX | — | 47% |
| SciCode | — | 56% |
Use-case scores are 0–100 percentile composites across each area’s benchmarks, ranked against every model from the past year. Highlighted cells lead each row. Open a model for the full picture.
Frequently asked questions
Is Claude Sonnet 4.5 better than GPT-6 Astra?
On Epoch AI's Capabilities Index, GPT-6 Astra scores higher (169) than Claude Sonnet 4.5 (147). The right pick depends on your task — compare their coding, math, and reasoning scores in the table above.
Which is cheaper, Claude Sonnet 4.5 or GPT-6 Astra?
Claude Sonnet 4.5 is cheaper on input tokens at $3.00 per million, versus $10.00 (representative OpenRouter pricing).
Which has a larger context window, Claude Sonnet 4.5 or GPT-6 Astra?
GPT-6 Astra supports up to 1.1M tokens, compared with 1M for the other.
Which is better for coding, Claude Sonnet 4.5 or GPT-6 Astra?
Across coding benchmarks like SWE-bench Verified and Terminal-Bench, GPT-6 Astra ranks higher — 95th vs 26th percentile among the models tracked on Model Beat.
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Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.