GPT-5.5 Instant vs GPT-5 Pro
GPT-5.5 Instant Verdict
- GPT-5.5 Instant and GPT-5 Pro are level on quality (60.5 vs 60.8).
- GPT-5.5 Instant is stronger in agents & tools, coding, composite, human preference, instruction following, knowledge, long context, maths, reasoning.
- GPT-5 Pro is stronger in multimodal.
- GPT-5.5 Instant is 3.7× cheaper ($11.25 vs $41.25 per 1M blended).
| Metric | GPT-5.5 Instant | GPT-5 Pro |
|---|---|---|
| BenchLeader Index | 60.5 | 60.8 |
| Agents & tools score | 70.7 | – |
| Coding score | 61.1 | – |
| Composite score | 62.9 | – |
| Human preference score | 67.5 | – |
| Instruction following score | 69.8 | – |
| Knowledge score | 69.4 | 68.0 |
| Long context score | 61.4 | – |
| Maths score | 42.5 | – |
| Multimodal score | 59.7 | 67.4 |
| Reasoning score | 62.6 | 57.6 |
| Blended price $/M | $11.25 | $41.25 |
| Output speed | 129 tok/s | – |
| Time to first answer | 16.8 s | – |
| Context window | 400k | 400k |
| GPQA Diamond | 82.5% | – |
| FrontierMath Tiers 1–3 | 26.3% | – |
| FrontierMath Tier 4 | 2.4% | – |
| OTIS Mock AIME | 68.1% | – |
| Humanity's Last Exam | – | 31.6% |
| SimpleBench | – | 61.6% |
| SciCode | 48.6% | – |
| Epoch Capabilities Index | 142.5 | 150.3 |
| LMArena Text | 1474 | – |
| LMArena Hard Prompts | 1491 | – |
| LMArena Coding | 1514 | – |
| LMArena Vision | 1251 | – |
| 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% | – |
| PRBench Finance | – | 51.1% |
| PRBench Legal | – | 49.9% |
| VISTA | – | 52.4% |
| MultiNRC | – | 65.2% |
| Kagi LLM Benchmark | – | 76.8% |
| ARC-AGI-1 | – | 70.2% |
| ARC-AGI-2 | – | 18.3% |
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 Pro: questions
- Is GPT-5.5 Instant better than GPT-5 Pro?
- GPT-5.5 Instant and GPT-5 Pro are level on quality (60.5 vs 60.8). The BenchLeader Index combines every independent quality benchmark; GPT-5 Pro is ahead overall as of 2026-09-10, but check the category scores for your use.
- Which is cheaper, GPT-5.5 Instant or GPT-5 Pro?
- GPT-5.5 Instant is cheaper: $11.25 against $41.25 per million tokens, blended at three input tokens per output token.
- Which has the larger context window?
- Both accept 400k tokens of context.