GPT-5.5 vs o3
GPT-5.5 Verdict
- GPT-5.5 leads on quality: 66.7 vs 60.4.
- GPT-5.5 is stronger in composite, human preference, instruction following, knowledge, long context, multimodal, reasoning.
- o3 is stronger in agents & tools, coding.
- o3 is 3.2× cheaper ($3.50 vs $11.25 per 1M blended).
| Metric | GPT-5.5 | o3 |
|---|---|---|
| BenchLeader Index | 66.7 | 60.4 |
| Agents & tools score | 68.5 | 70.3 |
| Coding score | 57.2 | 62.0 |
| Composite score | 77.8 | 54.5 |
| Human preference score | 67.9 | 62.4 |
| Instruction following score | 73.6 | 69.8 |
| Knowledge score | 73.9 | 57.9 |
| Long context score | 68.8 | 63.8 |
| Multimodal score | 64.9 | 57.9 |
| Reasoning score | 70.1 | 61.6 |
| Blended price $/M | $11.25 | $3.50 |
| Output speed | 85 tok/s | 101 tok/s |
| Time to first answer | 58.6 s | 7.7 s |
| Context window | 1.1M | 200k |
| Terminal-Bench | 84.7% | – |
| SimpleBench | 69.0% | – |
| Remote Labor Index | 6.3% | – |
| APEX-Agents | 38.5% | – |
| FrontierCode | 43.0% | – |
| Epoch Capabilities Index | 159.1 | 146.9 |
| LMArena Text | 1477 | 1431 |
| LMArena Hard Prompts | 1498 | 1441 |
| LMArena Coding | 1509 | 1460 |
| LMArena WebDev | 1458 | – |
| LMArena Vision | 1296 | 1214 |
| LMArena Agent | 3 | – |
| AA Intelligence Index | 38.6 | 20.2 |
| IFBench | 75.8% | 71.4% |
| AA-LCR | 84.3% | 74.7% |
| MMMU-Pro | 79.9% | 70.1% |
| AA-Omniscience | 20.5 | -15.6 |
| Terminal-Bench Hard | 60.6% | 37.1% |
| GPQA Diamond (AA) | 93.5% | 82.7% |
| Humanity's Last Exam (AA) | 45.8% | 20.1% |
| SciCode (AA) | 55.8% | – |
| τ²-Bench Telecom (AA) | 93.9% | 80.7% |
| PRBench Finance | – | 47.7% |
| PRBench Legal | – | 48.6% |
| HiL-Bench | 39.7% | – |
| EQ-Bench 4 | 1315 | – |
| MMMU (validation) | – | 82.9% |
| MMMU-Pro (official) | – | 76.4% |
| Kagi LLM Benchmark | 88.8% | 67.6% |
| 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 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 vs o3: questions
- Is GPT-5.5 better than o3?
- GPT-5.5 leads on quality: 66.7 vs 60.4. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is GPT-5.5 better than o3 for coding?
- o3 scores higher in coding (62 vs 57 on the category index, where 50 is average).
- Is GPT-5.5 better than o3 for agentic tasks?
- o3 scores higher in agentic tasks (70 vs 69 on the category index, where 50 is average).
- Which is cheaper, GPT-5.5 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 or o3?
- o3 streams faster: 101 against 85 output tokens per second.
- Which has the larger context window?
- GPT-5.5 accepts more context: 1.1M against 200k tokens.