GPT-5.5 Instant vs GPT-5.6 Sol
GPT-5.5 Instant Verdict
- GPT-5.6 Sol (high) leads on quality: 68.2 vs 60.5.
- GPT-5.5 Instant is stronger in human preference, instruction following, maths.
- GPT-5.6 Sol (high) is stronger in agents & tools, coding, composite, knowledge, long context, multimodal, reasoning.
- GPT-5.6 Sol (high) is 1.4× cheaper ($8.00 vs $11.25 per 1M blended).
- GPT-5.5 Instant streams 2.2× faster (129 vs 59 tokens per second).
| Metric | GPT-5.5 Instant | GPT-5.6 Sol (high) |
|---|---|---|
| BenchLeader Index | 60.5 | 68.2 |
| Agents & tools score | 70.7 | 87.9 |
| Coding score | 61.1 | 72.4 |
| Composite score | 62.9 | 82.7 |
| Human preference score | 67.5 | – |
| Instruction following score | 69.8 | 67.8 |
| Knowledge score | 69.4 | 73.8 |
| Long context score | 61.4 | 67.4 |
| Maths score | 42.5 | – |
| Multimodal score | 59.7 | 66.4 |
| Reasoning score | 62.6 | 63.3 |
| Blended price $/M | $11.25 | $8.00 |
| Output speed | 129 tok/s | 59 tok/s |
| Time to first answer | 16.8 s | 31.0 s |
| Context window | 400k | 1M |
| GPQA Diamond | 82.5% | – |
| FrontierMath Tiers 1–3 | 26.3% | – |
| FrontierMath Tier 4 | 2.4% | – |
| OTIS Mock AIME | 68.1% | – |
| SciCode | 48.6% | 56.9% |
| WeirdML | – | 88.8% |
| Epoch Capabilities Index | 142.5 | – |
| LMArena Text | 1474 | – |
| LMArena Hard Prompts | 1491 | – |
| LMArena Coding | 1514 | – |
| LMArena Vision | 1251 | – |
| AA Intelligence Index | 26.8 | 42.5 |
| IFBench | 71.5% | 69.2% |
| AA-LCR | 70.0% | 81.7% |
| MMMU-Pro | – | 81.8% |
| AA-Omniscience | 11.2 | 20.4 |
| Terminal-Bench Hard | 42.4% | 62.1% |
| GPQA Diamond (AA) | 84.7% | 92.8% |
| Humanity's Last Exam (AA) | 21.6% | 46.0% |
| SciCode (AA) | 52.5% | 57.8% |
| τ²-Bench Telecom (AA) | 49.4% | 83.3% |
| EnigmaEval | – | 37.1% |
| ARC-AGI-1 | – | 97.0% |
| ARC-AGI-2 | – | 85.4% |
| ARC-AGI-3 | – | 2.2% |
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-5.6 Sol: questions
- Is GPT-5.5 Instant better than GPT-5.6 Sol?
- GPT-5.6 Sol (high) leads on quality: 68.2 vs 60.5. The BenchLeader Index combines every independent quality benchmark; GPT-5.6 Sol (high) is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is GPT-5.5 Instant better than GPT-5.6 Sol for coding?
- GPT-5.6 Sol scores higher in coding (72 vs 61 on the category index, where 50 is average).
- Is GPT-5.5 Instant better than GPT-5.6 Sol for agentic tasks?
- GPT-5.6 Sol scores higher in agentic tasks (88 vs 71 on the category index, where 50 is average).
- Which is cheaper, GPT-5.5 Instant or GPT-5.6 Sol?
- GPT-5.6 Sol is cheaper: $8.00 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.5 Instant or GPT-5.6 Sol?
- GPT-5.5 Instant streams faster: 129 against 59 output tokens per second.
- Which has the larger context window?
- GPT-5.6 Sol accepts more context: 1M against 400k tokens.