Claude Opus 4.8 vs GPT-5.5 Instant
Claude Opus 4.8 
GPT-5.5 Instant Verdict
- Claude Opus 4.8 leads on quality: 64.8 vs 60.5.
- Claude Opus 4.8 is stronger in coding, composite, long context, multimodal, reasoning.
- GPT-5.5 Instant is stronger in agents & tools, human preference, instruction following, knowledge, maths.
- They cost about the same ($10.00 per 1M blended).
- GPT-5.5 Instant streams 2.3× faster (129 vs 56 tokens per second).
| Metric | Claude Opus 4.8 | GPT-5.5 Instant |
|---|---|---|
| BenchLeader Index | 64.8 | 60.5 |
| Agents & tools score | 65.0 | 70.7 |
| Coding score | 65.6 | 61.1 |
| Composite score | 82.1 | 62.9 |
| Human preference score | 65.8 | 67.5 |
| Instruction following score | 61.8 | 69.8 |
| Knowledge score | 66.5 | 69.4 |
| Long context score | 65.4 | 61.4 |
| Multimodal score | 64.5 | 59.7 |
| Reasoning score | 64.6 | 62.6 |
| Maths score | – | 42.5 |
| Blended price $/M | $10.00 | $11.25 |
| Output speed | 56 tok/s | 129 tok/s |
| Time to first answer | 29.3 s | 16.8 s |
| Context window | 1M | 400k |
| GPQA Diamond | – | 82.5% |
| FrontierMath Tiers 1–3 | – | 26.3% |
| FrontierMath Tier 4 | – | 2.4% |
| OTIS Mock AIME | – | 68.1% |
| SimpleBench | 64.8% | – |
| SciCode | – | 48.6% |
| Remote Labor Index | 8.3% | – |
| FrontierCode | 46.5% | – |
| GSO-Bench | 47.1% | – |
| Epoch Capabilities Index | 158.3 | 142.5 |
| LMArena Text | 1473 | 1474 |
| LMArena Hard Prompts | 1503 | 1491 |
| LMArena Coding | 1527 | 1514 |
| LMArena WebDev | 1540 | – |
| LMArena Vision | 1289 | 1251 |
| AA Intelligence Index | 42.0 | 26.8 |
| IFBench | 62.2% | 71.5% |
| AA-LCR | 77.7% | 70.0% |
| AA-Omniscience | 28.8 | 11.2 |
| Terminal-Bench Hard | 58.3% | 42.4% |
| GPQA Diamond (AA) | 92.0% | 84.7% |
| Humanity's Last Exam (AA) | 48.7% | 21.6% |
| SciCode (AA) | 54.4% | 52.5% |
| τ²-Bench Telecom (AA) | 94.4% | 49.4% |
| LiveCodeBench | 87.8% | – |
| MMLU-Pro | 89.6% | – |
| LegalBench | 83.6% | – |
| CorpFin | 66.7% | – |
| TaxEval | 75.6% | – |
| Terminal-Bench 2.1 (Vals) | 71.9% | – |
| SWE-bench (Vals) | 88.6% | – |
| GPQA Diamond (Vals) | 92.4% | – |
| Vals Index | 60.9 | – |
| HiL-Bench | 35.3% | – |
| EQ-Bench 4 | 1281 | – |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
Claude Opus 4.8 vs GPT-5.5 Instant: questions
- Is Claude Opus 4.8 better than GPT-5.5 Instant?
- Claude Opus 4.8 leads on quality: 64.8 vs 60.5. The BenchLeader Index combines every independent quality benchmark; Claude Opus 4.8 is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is Claude Opus 4.8 better than GPT-5.5 Instant for coding?
- Claude Opus 4.8 scores higher in coding (66 vs 61 on the category index, where 50 is average).
- Is Claude Opus 4.8 better than GPT-5.5 Instant for agentic tasks?
- GPT-5.5 Instant scores higher in agentic tasks (71 vs 65 on the category index, where 50 is average).
- Which is cheaper, Claude Opus 4.8 or GPT-5.5 Instant?
- Claude Opus 4.8 is cheaper: $10.00 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Opus 4.8 or GPT-5.5 Instant?
- GPT-5.5 Instant streams faster: 129 against 56 output tokens per second.
- Which has the larger context window?
- Claude Opus 4.8 accepts more context: 1M against 400k tokens.