Model comparison
Claude Opus 5.5 vs Gemini 3.5 Flash
Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 54.2 on the Noometry Index. Gemini 3.5 Flash costs 2.4× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Last verified . 37 shared benchmarks.
GoogleSummary
- They share 37 benchmarks with published results for both. Claude Opus 5.5 scores higher in 10 categories and Gemini 3.5 Flash in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 91.8 to 60.7.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Opus 5.5 and 31% for Gemini 3.5 Flash.
- Gemini 3.5 Flash is cheaper at $1.50 / $9 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
- Gemini 3.5 Flash accepts more context: 1.05M tokens versus 1M.
Side by side
| Claude Opus 5.5 | Gemini 3.5 Flash | |
|---|---|---|
| Provider | Anthropic | |
| Noometry Index | 68.6 | 54.2 |
| Released | 2026-09-22 | 2026-05-19 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1.05M |
| Max output | 128K | 66K |
| Input $ / M tokens | $4 | $1.50 |
| Output $ / M tokens | $20 | $9 |
| Results tracked | 44 | 54 |
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Category by category
Coding Claude Opus 5.5 leads
Claude Opus 5.5: 71.9 (#3), Gemini 3.5 Flash: 49.4 (#49)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| LMArena WebDev | 1813 | 1499 |
| SciCode | 66.9% | 53.1% |
| LMArena Coding | 1547 | 1492 |
| ALE-Bench | 2,147 | 911.02 |
| SWE-bench Verified | — | 79.3% |
| DeepSWE | — | 37.4% |
| FrontierCode | 54.6% | — |
| CursorBench | 57.8% | — |
| FrontierSWE | 62.3% | — |
| WeirdML | — | 62.6% |
| MirrorCode | 77.4% | — |
Agentic & Tool Use Claude Opus 5.5 leads
Claude Opus 5.5: 45.3 (#15), Gemini 3.5 Flash: 24.7 (#114)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| APEX-Agents | 73.5% | 27.5% |
| GDP.pdf | 30.6% | 14% |
| Vending-Bench 2 | 9,235 | 5,396 |
| GBAEval | — | 6.7% |
Reasoning Claude Opus 5.5 leads
Claude Opus 5.5: 80.2 (#3), Gemini 3.5 Flash: 62.8 (#18)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| ARC-AGI-2 | 93.3% | 72.1% |
| NYT Connections (extended) | 88.5% | 92.6% |
| ARC-AGI-1 | 98.5% | 92.5% |
| CritPt | 31.7% | 13.1% |
| EBR-Bench | 71.4% | 4.8% |
| LMArena Hard Prompts | 1535 | 1488 |
| Mystery Game Puzzles | 71% | 32% |
| DTBench | 98.9% | 94.7% |
| LMCA | 68.2% | 47.1% |
| Epoch Capabilities Index | 167.33 | 154.46 |
| SimpleBench | — | 76.7% |
| Chess Puzzles | — | 50% |
| EnigmaEval | — | 25.4% |
| Surface Evolver Bench | — | 58.1% |
| ForecastBench | — | 59 |
Math Claude Opus 5.5 leads
Claude Opus 5.5: 91.8 (#3), Gemini 3.5 Flash: 60.7 (#36)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | 62.8% |
| FrontierMath Tier 4 | 95% | 26.8% |
| OTIS Mock AIME 2024-2025 | 100% | 95.6% |
| ProofBench | 100% | 31% |
| LMArena Math | 1506 | 1504 |
| MathArena Final-Answer Competitions | — | 76.3% |
| FrontierMath (Feb 2025 set) | — | 39% |
| FrontierMath Erdős | 2.9% | — |
| FrontierMath Tier 4 (v1) | — | 14.6% |
Knowledge Too close to call
Claude Opus 5.5: 66.4 (#10), Gemini 3.5 Flash: 66.3 (#11)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| GPQA Diamond | 90.6% | 92.8% |
| SimpleQA Verified | 72.2% | 66.2% |
| LMArena Expert | 1547 | 1495 |
Multimodal Claude Opus 5.5 leads
Claude Opus 5.5: 57.8 (#1), Gemini 3.5 Flash: 45.7 (#15)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| LMArena Vision | 1321 | 1310 |
| Blueprint-Bench 2 | 51.2% | 33.6% |
| Furniture Assembly | 83.3% | — |
| LMArena Document | — | 1463 |
Multilingual Claude Opus 5.5 leads
Claude Opus 5.5: 59.1 (#2), Gemini 3.5 Flash: 57.0 (#13)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1507 | 1476 |
| LMArena Chinese | 1588 | 1526 |
| LMArena French | 1514 | 1490 |
| LMArena Russian | 1520 | 1493 |
| LMArena Spanish | 1507 | 1480 |
| LMArena German | — | 1492 |
| LMArena Japanese | — | 1486 |
| LMArena Korean | — | 1451 |
Instruction Following Claude Opus 5.5 leads
Claude Opus 5.5: 80.0 (#3), Gemini 3.5 Flash: 77.0 (#30)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1537 | 1467 |
Long Context Claude Opus 5.5 leads
Claude Opus 5.5: 47.1 (#19), Gemini 3.5 Flash: 45.4 (#38)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1532 | 1482 |
Writing & Preference Claude Opus 5.5 leads
Claude Opus 5.5: 78.2 (#3), Gemini 3.5 Flash: 65.5 (#47)
| Benchmark | Claude Opus 5.5 | Gemini 3.5 Flash |
|---|---|---|
| LMArena Text | 1515 | 1482 |
| LMArena Creative Writing | 1533 | 1470 |
| LMArena Multi-Turn | 1499 | 1481 |
| EQ-Bench Creative Writing | 2050 | — |
| EQ-Bench 4 | — | 1087 |
Frequently asked questions
Is Claude Opus 5.5 better than Gemini 3.5 Flash?
Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 54.2 on the Noometry Index. Gemini 3.5 Flash costs 2.4× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Opus 5.5 or Gemini 3.5 Flash?
Gemini 3.5 Flash is cheaper. It lists at $1.50 per million input tokens and $9 per million output tokens; Claude Opus 5.5 lists at $4 and $20.
Is Claude Opus 5.5 or Gemini 3.5 Flash better for coding?
Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 49.4 in the Noometry coding category.
Which has the bigger context window?
Gemini 3.5 Flash does, with 1.05M tokens against 1M.
How many benchmarks do Claude Opus 5.5 and Gemini 3.5 Flash share?
37 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Gemini 3.5 Flash has 54.