Claude Sonnet 5.5 vs Gemini 3 Flash Preview
Updated October 21, 2026. 32 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
vs boards won of 32 shared
Decision reading
Pick Claude Sonnet 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 75.8 for Gemini 3 Flash Preview.
Pick Gemini 3 Flash Preview when output tokens cost 3.3x less, or when the context window is larger, 1.05M against 1M tokens.
Model AClaude Sonnet 5.5Anthropic88.9/1002 independent benchmarksNo cost per solved taskModel BGemini 3 Flash PreviewGoogle75.8/1001 independent benchmark$0.37 per solved task
- Shared results
- 32
- Claude Sonnet 5.5 only
- 63
- Gemini 3 Flash Preview only
- 37
- Like-for-like categories
- 8 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, four public coding benchmarks
Claude Sonnet 5.5
Claude Sonnet 5.5 scores 88.9 against 75.8.
2 and 1 benchmarks behind the scores
Intelligence
AA Intelligence Index
Claude Sonnet 5.5
Claude Sonnet 5.5 leads, 56.0 against 26.3.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only Gemini 3 Flash Preview has a GPQA Diamond result, 87.9%.
Directional only
Math
AIME
No call
Only Gemini 3 Flash Preview has a AIME result, 95.6%.
Directional only
Knowledge
MMLU Pro
No call
Only Gemini 3 Flash Preview has a MMLU Pro result, 88.6%.
Directional only
Web design
Design Arena: websites
Claude Sonnet 5.5
Claude Sonnet 5.5 leads, 1326 against 1196.
Same board, both measured
General
Vals Index
No call
Only Claude Sonnet 5.5 has a Vals Index result, 70.8%.
Directional only
Long documents
Listed context window
Gemini 3 Flash Preview
Gemini 3 Flash Preview takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 3 Flash Preview
Claude Sonnet 5.5 $0.0070, Gemini 3 Flash Preview $0.0020 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Gemini 3 Flash Preview has the number, $0.37.
Directional only
At a glance
- Coding index
- Claude Sonnet 5.5 88.9 from 2 benchmarks, Gemini 3 Flash Preview 75.8 from 1 benchmark.
- Widest category
- Math, 47.6 points apart on average over 4 shared benchmarks.
- Widest single gap
- ProofBench: Claude Sonnet 5.5 100.0% against Gemini 3 Flash Preview 15.0%, 85.0 points apart on a 0 to 100 scale.
- Output price
- Claude Sonnet 5.5 $10.00 against Gemini 3 Flash Preview $3.00 per million output tokens, 3.3x apart.
- Context window
- Claude Sonnet 5.5 takes 1M tokens, Gemini 3 Flash Preview 1.05M.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Claude Sonnet 5.5 | Bars | Gemini 3 Flash Preview | Ties |
|---|---|---|---|---|
| Coding | 5 | 0 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 7 | 0 | ||
| Reasoning | 4 | 0 | ||
| Math | 4 | 0 | ||
| Knowledge | 0 | 2 | ||
| Web design | 4 | 0 | ||
| General | 4 | 1 | ||
| All shared boards | 29 | 3 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index50
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| SWE-bench Verified | Not measured | 75.8% | Only Gemini 3 Flash Preview measured |
| LiveBench coding | 94.7% | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena WebDev | 1768 | Not measured | Only Claude Sonnet 5.5 measured |
| LiveCodeBench (Vals AI) | Not measured | 85.6% | Only Gemini 3 Flash Preview measured |
| SWE-bench Verified (Vals AI) | Not measured | 75.0% | Only Gemini 3 Flash Preview measured |
| Terminal-Bench 4 (Vals AI) | 64.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Vibe Code Bench (Vals AI) | 92.4% | 20.2% | Claude Sonnet 5.5 |
| Code migration (Vals AI) | 69.8% | 6.4% | Claude Sonnet 5.5 |
| ProgramBench (Vals AI) | 6.5% | 0.0% | Claude Sonnet 5.5 |
| IOI (Vals AI) | 83.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 83.2% | 53.9% | Claude Sonnet 5.5 |
| SWE-bench Multimodal (Vals AI) | 58.3% | Not measured | Only Claude Sonnet 5.5 measured |
| CyberBench (Vals AI) | 59.6% | Not measured | Only Claude Sonnet 5.5 measured |
| LiveCodeBench (Artificial Analysis run) | Not measured | 90.8% | Only Gemini 3 Flash Preview measured |
| SciCode | 61.0% | Not measured | Only Claude Sonnet 5.5 measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 38.6% | Only Gemini 3 Flash Preview measured |
| Terminal-Bench | Not measured | 64.3% | Only Gemini 3 Flash Preview measured |
| FrontierCode | 52.1% | Not measured | Only Claude Sonnet 5.5 measured |
| FrontierSWE | 61.9% | Not measured | Only Claude Sonnet 5.5 measured |
| GSO-Bench | Not measured | 9.8% | Only Gemini 3 Flash Preview measured |
| WeirdML | Not measured | 61.6% | Only Gemini 3 Flash Preview measured |
| ALE-Bench | 1819.1 | 1367.2 | Claude Sonnet 5.5 |
| LMArena Text: coding | 1513 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: software and IT | 1504 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena WebDev: React | 1817 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena WebDev: HTML | 1741 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena WebDev: from an image | 1737 | Not measured | Only Claude Sonnet 5.5 measured |
| Neither model has a result on the other 11 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | 56.0 | 26.3 | Claude Sonnet 5.5 |
| Epoch Capabilities Index | 166.2 | Not measured | Only Claude Sonnet 5.5 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1303 | 1111 | Claude Sonnet 5.5 |
| Design Arena: agents building full-stack apps | Not measured | 1063 | Only Gemini 3 Flash Preview measured |
| Design Arena: agents building mobile apps | 1265 | 1090 | Claude Sonnet 5.5 |
| Design Arena: agents building Android apps | Not measured | 1056 | Only Gemini 3 Flash Preview measured |
| Design Arena: agents building Godot games | Not measured | 1161 | Only Gemini 3 Flash Preview measured |
| Design Arena: PowerPoint slides | Not measured | 1036 | Only Gemini 3 Flash Preview measured |
| Design Arena: spreadsheets | 1245 | Not measured | Only Claude Sonnet 5.5 measured |
| LiveBench research | 83.6% | Not measured | Only Claude Sonnet 5.5 measured |
| LiveBench browser | 84.0% | Not measured | Only Claude Sonnet 5.5 measured |
| LiveBench long agentic | 78.8% | Not measured | Only Claude Sonnet 5.5 measured |
| SREBench (Vals AI) | 30.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Finance Agent (Vals AI) | 58.1% | 42.5% | Claude Sonnet 5.5 |
| Tax Agent Bench (Vals AI) | 42.0% | 11.8% | Claude Sonnet 5.5 |
| Legal Research Bench (Vals AI) | 48.1% | 18.3% | Claude Sonnet 5.5 |
| Harvey's Legal Agent Benchmark (Vals AI) | 10.4% | Not measured | Only Claude Sonnet 5.5 measured |
| Excel Modeling Benchmark (Vals AI) | 75.7% | 26.0% | Claude Sonnet 5.5 |
| BioMysteryBench (Vals AI) | 81.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Terminal-Bench-Science (Vals AI) | 47.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Vals Science Index | 59.1% | Not measured | Only Claude Sonnet 5.5 measured |
| τ²-Bench Telecom | Not measured | 80.4% | Only Gemini 3 Flash Preview measured |
| APEX-Agents | 75.5% | Not measured | Only Claude Sonnet 5.5 measured |
| BALROG | Not measured | 48.1% | Only Gemini 3 Flash Preview measured |
| DeepResearch Bench | Not measured | 49.8% | Only Gemini 3 Flash Preview measured |
| SpireClimb | 1.3% | Not measured | Only Claude Sonnet 5.5 measured |
| Vending-Bench 2 | $11,165 | $3,635 | Claude Sonnet 5.5 |
| Neither model has a result on the other 14 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 87.9% | Only Gemini 3 Flash Preview measured |
| LiveBench reasoning | 91.6% | Not measured | Only Claude Sonnet 5.5 measured |
| MysteryMechanism (Vals AI) | 49.1% | Not measured | Only Claude Sonnet 5.5 measured |
| MMMU Pro (Vals AI) | Not measured | 87.6% | Only Gemini 3 Flash Preview measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 89.8% | Only Gemini 3 Flash Preview measured |
| Humanity's Last Exam (Artificial Analysis run) | 55.0% | 36.6% | Claude Sonnet 5.5 |
| GPQA Diamond (Epoch AI run) | 95.6% | 89.4% | Claude Sonnet 5.5 |
| ARC-AGI | Not measured | 84.7% | Only Gemini 3 Flash Preview measured |
| ARC-AGI-2 | Not measured | 33.6% | Only Gemini 3 Flash Preview measured |
| SimpleBench | Not measured | 61.1% | Only Gemini 3 Flash Preview measured |
| Chess puzzles | 59.0% | 39.0% | Claude Sonnet 5.5 |
| Mystery game puzzles | 65.0% | 26.0% | Claude Sonnet 5.5 |
| VPCT | Not measured | 72.6% | Only Gemini 3 Flash Preview measured |
| LMArena Text: hard prompts | 1494 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: expert | 1531 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: hard prompts in English | 1502 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Vision: diagrams | 1329 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Vision: homework | 1331 | Not measured | Only Claude Sonnet 5.5 measured |
| Neither model has a result on the other 3 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| AIME | Not measured | 95.6% | Only Gemini 3 Flash Preview measured |
| MGSM (Vals AI) | Not measured | 93.3% | Only Gemini 3 Flash Preview measured |
| AA Math Index | Not measured | 97.0 | Only Gemini 3 Flash Preview measured |
| AIME 2025 (Artificial Analysis run) | Not measured | 97.0% | Only Gemini 3 Flash Preview measured |
| OTIS Mock AIME | 100.0% | 95.6% | Claude Sonnet 5.5 |
| FrontierMath, tiers 1 to 3 | 88.8% | 51.2% | Claude Sonnet 5.5 |
| FrontierMath, tier 4 | 80.5% | 17.1% | Claude Sonnet 5.5 |
| ProofBench | 100.0% | 15.0% | Claude Sonnet 5.5 |
| LMArena Text: math | 1497 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: mathematical work | 1510 | Not measured | Only Claude Sonnet 5.5 measured |
| Neither model has a result on the other 3 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 88.6% | Only Gemini 3 Flash Preview measured |
| LegalBench (Vals AI) | Not measured | 86.9% | Only Gemini 3 Flash Preview measured |
| CaseLaw (Vals AI) | Not measured | 55.8% | Only Gemini 3 Flash Preview measured |
| CorpFin (Vals AI) | Not measured | 66.4% | Only Gemini 3 Flash Preview measured |
| TaxEval (Vals AI) | Not measured | 73.9% | Only Gemini 3 Flash Preview measured |
| MortgageTax (Vals AI) | Not measured | 68.7% | Only Gemini 3 Flash Preview measured |
| MedQA (Vals AI) | Not measured | 95.8% | Only Gemini 3 Flash Preview measured |
| MedCode (Vals AI) | 52.9% | 55.9% | Gemini 3 Flash Preview |
| MMLU Pro (Artificial Analysis run) | Not measured | 89.0% | Only Gemini 3 Flash Preview measured |
| SimpleQA Verified | 46.5% | 66.8% | Gemini 3 Flash Preview |
| GeoBench | Not measured | 88.0% | Only Gemini 3 Flash Preview measured |
| LMArena Text: science | 1483 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: medicine and healthcare | 1464 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: legal and government | 1483 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: business and finance | 1468 | Not measured | Only Claude Sonnet 5.5 measured |
| Neither model has a result on the other 2 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| Design Arena: websites | 1326 | 1196 | Claude Sonnet 5.5 |
| Design Arena: UI components | 1367 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: game dev | 1469 | 1166 | Claude Sonnet 5.5 |
| Design Arena: data viz | 1389 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: 3D | 1458 | 1184 | Claude Sonnet 5.5 |
| Design Arena: all code categories | 1364 | 1189 | Claude Sonnet 5.5 |
| LiveBench design | 85.0% | Not measured | Only Claude Sonnet 5.5 measured |
| Neither model has a result on the other 2 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index41
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| Vals Index | 70.8% | Not measured | Only Claude Sonnet 5.5 measured |
| LiveBench data analysis | 59.5% | Not measured | Only Claude Sonnet 5.5 measured |
| Public Benefits Bench (Vals AI) | 67.2% | Not measured | Only Claude Sonnet 5.5 measured |
| SAGE (Vals AI) | 51.8% | 51.8% | Gemini 3 Flash Preview |
| MedScribe (Vals AI) | 91.1% | 69.9% | Claude Sonnet 5.5 |
| Vals Multimodal Index | Not measured | 52.2% | Only Gemini 3 Flash Preview measured |
| IFBench | Not measured | 78.0% | Only Gemini 3 Flash Preview measured |
| Long context reasoning (AA-LCR) | 82.7% | 78.0% | Claude Sonnet 5.5 |
| DTBench | 97.3% | 89.1% | Claude Sonnet 5.5 |
| LMCA | 68.3% | 43.1% | Claude Sonnet 5.5 |
| Furniture assembly | 75.0% | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text | 1473 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: instruction following | 1492 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: creative writing | 1467 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Vision | 1287 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: English | 1484 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: non-English | 1456 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: Chinese | 1535 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: French | 1499 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: Spanish | 1451 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: Russian | 1454 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: multi-turn | 1465 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: longer queries | 1495 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: writing and language | 1474 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: entertainment and media | 1461 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Vision: English | 1289 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Vision: reading text | 1297 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Vision: creative writing | 1242 | Not measured | Only Claude Sonnet 5.5 measured |
| Neither model has a result on the other 18 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Sonnet 5.5 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Claude Sonnet 5.5$0.0070Fits in one request
Gemini 3 Flash Preview$0.0020Fits in one request
Gemini 3 Flash Preview costs less
Repository review
50K input + 3K output tokens
Claude Sonnet 5.5$0.130Fits in one request
Gemini 3 Flash Preview$0.034Fits in one request
Gemini 3 Flash Preview costs less
Agent loop
200K input + 10K output tokens
Claude Sonnet 5.5$0.500Fits in one request
Gemini 3 Flash Preview$0.130Fits in one request
Gemini 3 Flash Preview costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Anthropic Claude Sonnet 5.5 | Google Gemini 3 Flash Preview |
|---|---|---|
| Maker | Anthropic | |
| Weights | No public weights listed | No public weights listed |
| Released | September 28, 2026 | December 17, 2025 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $2.00 | $0.50 |
| Output $/Mtok | $10.00 | $3.00 |
| Coding index | 88.9 | 75.8 |
| Independent measurements behind it | 2 | 1 |
| Cost per solved task | Not computable | $0.37 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Sonnet 5.5 better than Gemini 3 Flash Preview for coding?
Pick Claude Sonnet 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 75.8 for Gemini 3 Flash Preview. Pick Gemini 3 Flash Preview when output tokens cost 3.3x less, or when the context window is larger, 1.05M against 1M tokens.
Which is cheaper, Claude Sonnet 5.5 or Gemini 3 Flash Preview?
Claude Sonnet 5.5 costs $2.00 per million input tokens and $10.00 per million output tokens; Gemini 3 Flash Preview costs $0.50 and $3.00. Cost per solved task is known for Gemini 3 Flash Preview only.
Which has the bigger context window, Claude Sonnet 5.5 or Gemini 3 Flash Preview?
Gemini 3 Flash Preview, with 1.05M tokens against 1M.
How many benchmarks is the Claude Sonnet 5.5 vs Gemini 3 Flash Preview comparison based on?
32 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 5.5's coding index rests on 2 independent benchmarks and Gemini 3 Flash Preview's on 1. Where only one model has a result, the page says so instead of naming a winner.