Comparing 2 models
Claude Opus 5.5 vs Gemini 3.5 Flash
Benchmarks through
Verdict
Claude Opus 5.5 places higher on 3 of the 3 tasks where both are ranked. Gemini 3.5 Flash costs 2.7x less per input token. Gemini 3.5 Flash accepts 1.0x more context.
- Choose Claude Opus 5.5 for Chat & Roleplay (#6), RAG & Long Context (#6), Roleplay & Character (#6).
Built from the published task rankings below; ranks come from each task's own weighted benchmarks, so a win on one task says nothing about another.
Measured head to head
Benchmarks both models were run on
| Evaluation | Claude Opus 5.5 | Gemini 3.5 Flash | Source |
|---|---|---|---|
| Design Arena Coding | 1392 Elo | 1268 Elo | source · 2026-10-16 |
| Design Arena UI | 1378 Elo | 1272 Elo | source · 2026-10-16 |
| Design Arena Website | 1338 Elo | 1269 Elo | source · 2026-10-16 |
| FACTS Grounding | 68.5% | 73.2% | source · 2026-09-24 |
| FrontierMath Tiers 1-3 (Epoch AI) | 91.2% ± 1.7 | 62.8% ± 2.9 | source · 2026-09-22 |
| GPQA Diamond (Epoch AI) | 90.6% ± 1.9 | 92.8% ± 1.6 | source · 2026-09-22 |
| LiveBench Agentic Coding | 71.7% | 49.0% | source · 2026-10-16 |
| LiveBench Coding | 89.3% | 78.2% | source · 2026-10-16 |
| LiveBench Data Analysis | 80.3% | 64.9% | source · 2026-10-16 |
| LiveBench Instruction Following | 65.7% | 75.6% | source · 2026-10-16 |
| LiveBench Language | 86.3% | 84.6% | source · 2026-10-16 |
| LiveBench Math | 97.1% | 88.2% | source · 2026-10-16 |
| LiveBench Reasoning | 92.2% | 82% | source · 2026-10-16 |
| LMArena Creative Writing | 1534 Elo | 1468 Elo | source · 2026-10-15 |
| LMArena Instruction Following | 1536 Elo | 1467 Elo | source · 2026-10-15 |
| LMArena Long Query | 1531 Elo | 1483 Elo | source · 2026-10-15 |
| LMArena Math | 1508 Elo | 1503 Elo | source · 2026-10-15 |
| LMArena Text | 1508 Elo | 1477 Elo | source · 2026-10-15 |
| LMArena Text Factuality | 1509 Elo | 1477 Elo | source · 2026-10-15 |
| LMArena Vision | 1293 Elo | 1284 Elo | source · 2026-10-09 |
| LMArena Vision Diagrams | 1324 Elo | 1309 Elo | source · 2026-10-09 |
| LMArena Vision OCR | 1307 Elo | 1293 Elo | source · 2026-10-09 |
| LMArena WebDev | 1811 Elo | 1499 Elo | source · 2026-10-13 |
| LMArena WebDev Image-to-Web | 1749 Elo | 1501 Elo | source · 2026-10-09 |
| OTIS Mock AIME (Epoch AI) | 100% ± 0 | 95.6% ± 2.7 | source · 2026-09-22 |
| SimpleQA Verified (Epoch AI) | 72.2% ± 1.4 | 66.2% ± 1.5 | source · 2026-09-22 |
Values are as published by each evaluator, in its own units; rows from different evaluators are not on a common scale.
task evidence
How they place when the question changes
Lower ranks are better. “Best” marks the strongest option in this shortlist for that task.