GPT-5.5 Pro vs o3
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 60.3.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- o3 is stronger in agents & tools, coding, composite, human preference, instruction following, knowledge, long context, multimodal.
- o3 is 19× cheaper ($3.50 vs $67.50 per 1M blended).
- o3 streams 31.8× faster (127 vs 4 tokens per second).
| Metric | GPT-5.5 Pro (xhigh) | o3 |
|---|---|---|
| BenchLeader Index | 67.1 | 60.3 |
| Maths score | 74.5 | 71.2 |
| Reasoning score | 80.1 | 52.9 |
| Agents & tools score | – | 70.2 |
| Coding score | – | 61.9 |
| Composite score | – | 54.6 |
| Human preference score | – | 62.2 |
| Instruction following score | – | 65.1 |
| Knowledge score | – | 57.2 |
| Long context score | – | 63.7 |
| Multimodal score | – | 57.7 |
| Blended price $/M | $67.50 | $3.50 |
| Output speed | 4 tok/s | 127 tok/s |
| Time to first answer | 3.5 s | 5.9 s |
| Context window | 1.1M | 200k |
| FrontierMath Tiers 1–3 | 87.7% | – |
| FrontierMath Tier 4 | 78.0% | – |
| Epoch Capabilities Index | – | 146.9 |
| LMArena Text | – | 1432 |
| LMArena Hard Prompts | – | 1441 |
| LMArena Coding | – | 1460 |
| LMArena Vision | – | 1214 |
| AA Intelligence Index | – | 20.2 |
| IFBench | – | 71.4% |
| AA-LCR | – | 74.7% |
| MMMU-Pro | – | 70.1% |
| AA-Omniscience | – | -15.6 |
| Terminal-Bench Hard | – | 37.1% |
| GPQA Diamond (AA) | – | 82.7% |
| Humanity's Last Exam (AA) | – | 20.1% |
| τ²-Bench Telecom (AA) | – | 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% |
| ARC-AGI-1 | 95.0% | – |
| ARC-AGI-2 | 84.2% | – |
| BFCL Overall | – | 63.0% |
| CritPt | 30.6% | 1.1% |
| FORTRESS | – | 16.0% |
| PropensityBench | – | 10.5% |
| SciPredict | – | 17.9% |
| VTB | – | 13.7% |
| LMArena Maths | – | 1448 |
| LMArena Creative Writing | – | 1382 |
| LMArena Instruction Following | – | 1402 |
| LMArena Multi-turn | – | 1420 |
| LMArena Longer Queries | – | 1410 |
| METR Time Horizons | – | 63.6% |
| LMCA | 53.9% | – |
| DTBench | 96.0% | – |
| ForecastBench | – | 62.5% |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 Pro vs o3: questions
- Is GPT-5.5 Pro better than o3?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 60.3. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 Pro (xhigh) is ahead overall as of 2026-09-19, but check the category scores for your use.
- Which is cheaper, GPT-5.5 Pro or o3?
- o3 is cheaper: $3.50 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.5 Pro or o3?
- o3 streams faster: 127 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 200k tokens.