GPT-5 vs GPT-5.5 Instant
GPT-5 Verdict
- GPT-5 and GPT-5.5 Instant are level on quality (60.7 vs 60.5).
- GPT-5 is stronger in long context, maths, multimodal, reasoning.
- GPT-5.5 Instant is stronger in agents & tools, coding, composite, human preference, instruction following, knowledge.
- GPT-5 is 3.3× cheaper ($3.44 vs $11.25 per 1M blended).
| Metric | GPT-5 | GPT-5.5 Instant |
|---|---|---|
| BenchLeader Index | 60.7 | 60.5 |
| Agents & tools score | 51.0 | 70.7 |
| Coding score | 60.9 | 61.0 |
| Composite score | 58.1 | 63.0 |
| Human preference score | 61.7 | 67.4 |
| Instruction following score | 65.0 | 69.8 |
| Knowledge score | 61.6 | 69.6 |
| Long context score | 65.6 | 61.3 |
| Maths score | 72.8 | 42.5 |
| Multimodal score | 59.5 | 59.3 |
| Reasoning score | 64.1 | 62.5 |
| Blended price $/M | $3.44 | $11.25 |
| Output speed | 107 tok/s | 131 tok/s |
| Time to first answer | 55.3 s | 16.4 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% |
| Terminal-Bench | 49.6% | – |
| SciCode | 42.9% | 48.6% |
| Remote Labor Index | 1.7% | – |
| WeirdML | 39.8% | – |
| APEX-Agents | 18.3% | – |
| Epoch Capabilities Index | 150 | 142.5 |
| LMArena Text | 1427 | 1474 |
| LMArena Hard Prompts | 1449 | 1491 |
| LMArena Coding | 1463 | 1514 |
| LMArena Vision | 1231 | 1251 |
| AA Intelligence Index | 23.0 | 26.8 |
| IFBench | 73.1% | 71.5% |
| AA-LCR | 78.2% | 70.0% |
| MMMU-Pro | 74.2% | – |
| AA-Omniscience | -8.7 | 11.2 |
| Terminal-Bench Hard | 32.6% | 42.4% |
| GPQA Diamond (AA) | 85.3% | 84.7% |
| Humanity's Last Exam (AA) | 28.5% | 21.6% |
| SciCode (AA) | – | 52.5% |
| τ²-Bench Telecom (AA) | 84.8% | 49.4% |
| PRBench Finance | 51.3% | – |
| PRBench Legal | 49.0% | – |
| VISTA | 49.7% | – |
| MultiNRC | 52.1% | – |
| TutorBench | 55.3% | – |
| Kagi LLM Benchmark | 72.7% | – |
| IFEval (HELM) | 87.5% | – |
| Omni-MATH (HELM) | 64.7% | – |
| WildBench (HELM) | 85.7% | – |
| MMLU-Pro (HELM) | 86.3% | – |
| GPQA Diamond (HELM) | 79.1% | – |
| HELM Capabilities mean | 80.7% | – |
| Aider Polyglot | 88.0% | – |
| SWE-bench Verified (any scaffold) | 75.6% | – |
Data as of 2026-09-15. Best configuration of each model; every score links to its source on the model pages.
GPT-5 vs GPT-5.5 Instant: questions
- Is GPT-5 better than GPT-5.5 Instant?
- GPT-5 and GPT-5.5 Instant are level on quality (60.7 vs 60.5). The BenchLeader Index combines every independent quality benchmark; GPT-5 is ahead overall as of 2026-09-15, but check the category scores for your use.
- Is GPT-5 better than GPT-5.5 Instant for coding?
- GPT-5.5 Instant scores higher in coding (61 vs 61 on the category index, where 50 is average).
- Is GPT-5 better than GPT-5.5 Instant for agentic tasks?
- GPT-5.5 Instant scores higher in agentic tasks (71 vs 51 on the category index, where 50 is average).
- Which is cheaper, GPT-5 or GPT-5.5 Instant?
- GPT-5 is cheaper: $3.44 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5 or GPT-5.5 Instant?
- GPT-5.5 Instant streams faster: 131 against 107 output tokens per second.
- Which has the larger context window?
- Both accept 400k tokens of context.