GPT-5.5 Instant vs GPT-6 Astra
GPT-5.5 Instant Verdict
- GPT-6 Astra (max) leads on quality: 70.9 vs 60.5.
- GPT-5.5 Instant is stronger in agents & tools, human preference, instruction following, long context, multimodal.
- GPT-6 Astra (max) is stronger in coding, composite, knowledge, maths, reasoning.
- GPT-5.5 Instant is 1.8× cheaper ($11.25 vs $20.00 per 1M blended).
- GPT-5.5 Instant streams 4.8× faster (129 vs 27 tokens per second).
| Metric | GPT-5.5 Instant | GPT-6 Astra (max) |
|---|---|---|
| BenchLeader Index | 60.5 | 70.9 |
| Agents & tools score | 70.7 | 68.2 |
| Coding score | 61.1 | 78.6 |
| Composite score | 62.9 | 72.9 |
| Human preference score | 67.5 | – |
| Instruction following score | 69.8 | – |
| Knowledge score | 69.4 | 80.0 |
| Long context score | 61.4 | – |
| Maths score | 42.5 | 77.2 |
| Multimodal score | 59.7 | – |
| Reasoning score | 62.6 | 73.6 |
| Blended price $/M | $11.25 | $20.00 |
| Output speed | 129 tok/s | 27 tok/s |
| Time to first answer | 16.8 s | 337.3 s |
| Context window | 400k | 1.1M |
| GPQA Diamond | 82.5% | 95.8% |
| FrontierMath Tiers 1–3 | 26.3% | 93.7% |
| FrontierMath Tier 4 | 2.4% | 97.6% |
| OTIS Mock AIME | 68.1% | 100.0% |
| SimpleQA Verified | – | 75.6% |
| Terminal-Bench | – | 58.2% |
| SciCode | 48.6% | 56.5% |
| FrontierCode | – | 53.3% |
| Epoch Capabilities Index | 142.5 | – |
| LMArena Text | 1474 | – |
| LMArena Hard Prompts | 1491 | – |
| LMArena Coding | 1514 | – |
| LMArena WebDev | – | 1796 |
| LMArena Vision | 1251 | – |
| LMArena Agent | – | 12.5 |
| LiveBench | – | 82.2% |
| LiveBench Reasoning | – | 92.7% |
| LiveBench Coding | – | 80.4% |
| LiveBench Agentic Coding | – | 57.3% |
| LiveBench Mathematics | – | 96.8% |
| LiveBench Data Analysis | – | 83.0% |
| LiveBench Language | – | 89.4% |
| AA Intelligence Index | 26.8 | – |
| IFBench | 71.5% | – |
| AA-LCR | 70.0% | – |
| AA-Omniscience | 11.2 | – |
| Terminal-Bench Hard | 42.4% | – |
| GPQA Diamond (AA) | 84.7% | – |
| Humanity's Last Exam (AA) | 21.6% | – |
| SciCode (AA) | 52.5% | – |
| τ²-Bench Telecom (AA) | 49.4% | – |
| Terminal-Bench 2.1 (Vals) | – | 87.3% |
| Vals Index | – | 66.6 |
| ARC-AGI-1 | – | 97.5% |
| ARC-AGI-2 | – | 95.0% |
| ARC-AGI-3 | – | 98.6% |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 Instant vs GPT-6 Astra: questions
- Is GPT-5.5 Instant better than GPT-6 Astra?
- GPT-6 Astra (max) leads on quality: 70.9 vs 60.5. The BenchLeader Index combines every independent quality benchmark; GPT-6 Astra (max) is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is GPT-5.5 Instant better than GPT-6 Astra for coding?
- GPT-6 Astra scores higher in coding (79 vs 61 on the category index, where 50 is average).
- Is GPT-5.5 Instant better than GPT-6 Astra for agentic tasks?
- GPT-5.5 Instant scores higher in agentic tasks (71 vs 68 on the category index, where 50 is average).
- Which is cheaper, GPT-5.5 Instant or GPT-6 Astra?
- GPT-5.5 Instant is cheaper: $11.25 against $20.00 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.5 Instant or GPT-6 Astra?
- GPT-5.5 Instant streams faster: 129 against 27 output tokens per second.
- Which has the larger context window?
- GPT-6 Astra accepts more context: 1.1M against 400k tokens.