GPT-5.5 Instant vs o3
GPT-5.5 Instant Verdict
- o3 leads on quality: 61.5 vs 60.5.
- GPT-5.5 Instant is stronger in agents & tools, composite, human preference, instruction following, knowledge, multimodal, reasoning.
- o3 is stronger in coding, long context, maths.
- o3 is 3.2× cheaper ($3.50 vs $11.25 per 1M blended).
| Metric | GPT-5.5 Instant | o3 |
|---|---|---|
| BenchLeader Index | 60.5 | 61.5 |
| Agents & tools score | 70.7 | 70.3 |
| Coding score | 61.0 | 61.9 |
| Composite score | 63.0 | 54.6 |
| Human preference score | 67.4 | 62.2 |
| Instruction following score | 69.8 | 65.0 |
| Knowledge score | 69.6 | 57.2 |
| Long context score | 61.3 | 63.8 |
| Maths score | 42.5 | 78.6 |
| Multimodal score | 59.3 | 57.7 |
| Reasoning score | 62.5 | 61.5 |
| Blended price $/M | $11.25 | $3.50 |
| Output speed | 131 tok/s | 144 tok/s |
| Time to first answer | 16.4 s | 4.1 s |
| Context window | 400k | 200k |
| GPQA Diamond | 82.5% | – |
| FrontierMath Tiers 1–3 | 26.3% | – |
| FrontierMath Tier 4 | 2.4% | – |
| OTIS Mock AIME | 68.1% | – |
| SciCode | 48.6% | – |
| Epoch Capabilities Index | 142.5 | 146.9 |
| LMArena Text | 1474 | 1432 |
| LMArena Hard Prompts | 1491 | 1441 |
| LMArena Coding | 1514 | 1460 |
| LMArena Vision | 1251 | 1214 |
| AA Intelligence Index | 26.8 | 20.2 |
| IFBench | 71.5% | 71.4% |
| AA-LCR | 70.0% | 74.7% |
| MMMU-Pro | – | 70.1% |
| AA-Omniscience | 11.2 | -15.6 |
| Terminal-Bench Hard | 42.4% | 37.1% |
| GPQA Diamond (AA) | 84.7% | 82.7% |
| Humanity's Last Exam (AA) | 21.6% | 20.1% |
| SciCode (AA) | 52.5% | – |
| τ²-Bench Telecom (AA) | 49.4% | 80.7% |
| PRBench Finance | – | 47.7% |
| PRBench Legal | – | 48.6% |
| MMMU (validation) | – | 82.9% |
| MMMU-Pro (official) | – | 76.4% |
| Kagi LLM Benchmark | – | 67.6% |
| IFEval (HELM) | – | 86.9% |
| Omni-MATH (HELM) | – | 71.4% |
| WildBench (HELM) | – | 86.1% |
| MMLU-Pro (HELM) | – | 85.9% |
| GPQA Diamond (HELM) | – | 75.3% |
| HELM Capabilities mean | – | 81.1% |
| Aider Polyglot | – | 81.3% |
| SWE-bench Verified (bash only) | – | 58.4% |
| SWE-bench Verified (any scaffold) | – | 58.4% |
| BFCL Overall | – | 63.0% |
Data as of 2026-09-15. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 Instant vs o3: questions
- Is GPT-5.5 Instant better than o3?
- o3 leads on quality: 61.5 vs 60.5. The BenchLeader Index combines every independent quality benchmark; o3 is ahead overall as of 2026-09-15, but check the category scores for your use.
- Is GPT-5.5 Instant better than o3 for coding?
- o3 scores higher in coding (62 vs 61 on the category index, where 50 is average).
- Is GPT-5.5 Instant better than o3 for agentic tasks?
- GPT-5.5 Instant scores higher in agentic tasks (71 vs 70 on the category index, where 50 is average).
- Which is cheaper, GPT-5.5 Instant or o3?
- o3 is cheaper: $3.50 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.5 Instant or o3?
- o3 streams faster: 144 against 131 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Instant accepts more context: 400k against 200k tokens.