# Claude Sonnet 5.5 vs Gemini 2.5 Flash

> Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 39.0 on the Noometry Index. Gemini 2.5 Flash costs 4.7× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-sonnet-5-5-vs-gemini-2-5-flash
- Last updated: 2026-10-10
- Shared benchmarks: 3

## Summary

- They share 3 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 6 categories and Gemini 2.5 Flash in 0 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 88.7 to 38.1.
- The biggest single-benchmark swing is CritPt: 31.4% for Claude Sonnet 5.5 and 1.1% for Gemini 2.5 Flash.
- Gemini 2.5 Flash is cheaper at $0.30 / $2.50 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Gemini 2.5 Flash accepts more context: 1.05M tokens versus 1M.

## Snapshot

| | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| Provider | Anthropic | Google |
| Noometry Index | 60.5 | 39.0 |
| Rank | 10 | 162 |
| Context | 1M | 1.05M |
| Input $/M | $2 | $0.30 |
| Output $/M | $10 | $2.50 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Sonnet 5.5: 65.5 (#6)
- Gemini 2.5 Flash: 35.5 (#210)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| ALE-Bench | 1,819 | 661.88 |
| FrontierCode | 52.1% | — |
| SWE-bench Verified (bash only) | — | 28.7% |
| Aider Polyglot | — | 55.1% |
| CursorBench | 55.5% | — |
| LMArena WebDev | 1699 | — |
| FrontierSWE | 61.9% | — |
| SciCode | 61% | — |
| WeirdML | — | 41.9% |
| LMArena Coding | — | 1424 |

## Agentic & Tool Use

- Claude Sonnet 5.5: 44.9 (#14)
- Gemini 2.5 Flash: 30.6 (#67)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| Terminal-Bench | — | 17.1% |
| APEX-Agents | 75.5% | — |
| Berkeley Function Calling Leaderboard | — | 56.2% |
| TheAgentCompany | — | 41.1% |
| BALROG | — | 33.5% |
| Vending-Bench 2 | — | 548.84 |

## Reasoning

- Claude Sonnet 5.5: 52.4 (#29)
- Gemini 2.5 Flash: 18.2 (#271)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| CritPt | 31.4% | 1.1% |
| ARC-AGI-2 | — | 2.5% |
| SimpleBench | — | 41.2% |
| Kagi LLM Benchmark | — | 56.8% |
| ARC-AGI-1 | — | 33.3% |
| EnigmaEval | — | 2.7% |
| LMArena Hard Prompts | — | 1422 |
| Mystery Game Puzzles | 65% | — |
| DTBench | — | 76.5% |
| LMCA | — | 27.5% |
| Epoch Capabilities Index | — | 143.04 |
| ForecastBench | — | 60.6 |

## Math

- Claude Sonnet 5.5: 88.7 (#4)
- Gemini 2.5 Flash: 38.1 (#87)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 100% | 73.1% |
| FrontierMath (Tiers 1-3) | 88.8% | — |
| FrontierMath Tier 4 | 80.5% | — |
| ProofBench | 100% | — |
| Omni-MATH | — | 38.5% |
| LMArena Math | — | 1415 |
| FrontierMath (Feb 2025 set) | — | 4.8% |
| FrontierMath Tier 4 (v1) | — | 4.2% |

## Knowledge

- Claude Sonnet 5.5: 66.0 (#11)
- Gemini 2.5 Flash: 36.1 (#162)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| GPQA Diamond | 95.6% | — |
| Humanity's Last Exam | — | 12.1% |
| SimpleQA Verified | 46.5% | — |
| MMLU-Pro | — | 63.9% |
| Confabulations | — | 16.8% |
| Vectara Hallucination Rate | — | 7.8% |
| GPQA (HELM) | — | 39% |
| LMArena Expert | — | 1426 |

## Multimodal

- Claude Sonnet 5.5: 53.2 (#5)
- Gemini 2.5 Flash: 41.2 (#31)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| LMArena Vision | — | 1254 |
| GeoBench | — | 76% |
| VPCT | — | 46.2% |
| Furniture Assembly | 75% | — |
| SpatialViz-Bench | — | 36.9% |

## Multilingual

- Claude Sonnet 5.5: —
- Gemini 2.5 Flash: 52.5 (#83)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| LMArena Non-English | — | 1410 |
| LMArena Chinese | — | 1450 |
| LMArena French | — | 1433 |
| LMArena German | — | 1419 |
| LMArena Japanese | — | 1403 |
| LMArena Korean | — | 1385 |
| LMArena Russian | — | 1415 |
| LMArena Spanish | — | 1421 |

## Instruction Following

- Claude Sonnet 5.5: —
- Gemini 2.5 Flash: 75.9 (#50)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| IFEval | — | 89.8% |
| LMArena Instruction Following | — | 1405 |

## Long Context

- Claude Sonnet 5.5: —
- Gemini 2.5 Flash: 47.5 (#16)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| Fiction.LiveBench | — | 77.8% |
| LMArena Longer Query | — | 1419 |

## Writing & Preference

- Claude Sonnet 5.5: —
- Gemini 2.5 Flash: 54.0 (#153)

| Benchmark | Claude Sonnet 5.5 | Gemini 2.5 Flash |
|---|---|---|
| LMArena Text | — | 1417 |
| LMArena Creative Writing | — | 1400 |
| Short-Story Creative Writing | — | 76.5% |
| EQ-Bench Creative Writing | — | 1137 |
| WildBench | — | 81.7% |
| LMArena Multi-Turn | — | 1408 |

## FAQ

### Is Claude Sonnet 5.5 better than Gemini 2.5 Flash?

Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 39.0 on the Noometry Index. Gemini 2.5 Flash costs 4.7× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

### Which is cheaper, Claude Sonnet 5.5 or Gemini 2.5 Flash?

Gemini 2.5 Flash is cheaper. It lists at $0.30 per million input tokens and $2.50 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.

### Is Claude Sonnet 5.5 or Gemini 2.5 Flash better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 65.5 versus 35.5 in the Noometry coding category.

### Which has the bigger context window?

Gemini 2.5 Flash does, with 1.05M tokens against 1M.

### How many benchmarks do Claude Sonnet 5.5 and Gemini 2.5 Flash share?

3 benchmarks have published results for both models. Claude Sonnet 5.5 has 16 scored results on Noometry and Gemini 2.5 Flash has 54.