Claude Opus 5.5 vs Gemini 2.5 Flash
Claude Opus 5.5 leads Gemini 2.5 Flash on the Artificial Analysis Intelligence Index, 57.6 to 15.5, and Gemini 2.5 Flash costs 8.0x less per output token ($2.50 vs $20.00 per million). Updated October 22, 2026; 51 benchmarks have a result for both.
vs boards won of 51 shared
Claude Opus 5.5 or Gemini 2.5 Flash: which to pick
Only Claude Opus 5.5 has a coding score, 88.8 on the Vibe Coding Index; Gemini 2.5 Flash has none, so the two cannot be ranked on coding.
Pick Gemini 2.5 Flash for output tokens 8.0x cheaper ($2.50 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
Model AClaude Opus 5.5Anthropic88.8/1005 independent benchmarksNo cost per solved taskModel BGemini 2.5 FlashGoogleNot benchmarkedNo coding benchmark$0.466 per solved task
- Shared results
- 51
- Claude Opus 5.5 only
- 58
- Gemini 2.5 Flash only
- 22
- Like-for-like categories
- 8 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
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, six public coding benchmarks
No call
Only Claude Opus 5.5 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Claude Opus 5.5
Claude Opus 5.5 leads, 57.6 against 15.5.
Same board, both measured
Web design
Design Arena: websites
Claude Opus 5.5
Claude Opus 5.5 leads, 1335 against 1074.
Same board, both measured
General
Vals Index
No call
Only Claude Opus 5.5 has a Vals Index result, 70.2%.
Directional only
Long documents
Listed context window
Gemini 2.5 Flash
Gemini 2.5 Flash takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 2.5 Flash
Claude Opus 5.5 $0.014, Gemini 2.5 Flash $0.0015 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Gemini 2.5 Flash has the number, $0.466.
Directional only
At a glance
- Coding index
- Claude Opus 5.5 88.8 from 5 benchmarks, Gemini 2.5 Flash not benchmarked.
- Widest category
- Agentic work, 54.3 points apart on average over 1 shared benchmark.
- Widest single gap
- ARC-AGI-2: Claude Opus 5.5 93.3% against Gemini 2.5 Flash 2.5%, 90.8 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 5.5 $20.00 against Gemini 2.5 Flash $2.50 per million output tokens, 8.0x apart.
- Context window
- Claude Opus 5.5 takes 1M tokens, Gemini 2.5 Flash 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 Opus 5.5 | Bars | Gemini 2.5 Flash | Ties |
|---|---|---|---|---|
| Coding | 2 | 0 | ||
| Intelligence | 2 | 0 | ||
| Agentic work | 1 | 0 | ||
| Reasoning | 8 | 0 | ||
| Math | 2 | 0 | ||
| Knowledge | 6 | 0 | ||
| Web design | 7 | 0 | ||
| General | 23 | 0 | ||
| All shared boards | 51 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index20
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| SWE-bench Verified | Not measured | 28.7% | Only Gemini 2.5 Flash measured |
| LiveBench coding | 96.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev | 1807 | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench 4 (Vals AI) | 65.2% | Not measured | Only Claude Opus 5.5 measured |
| Vibe Code Bench (Vals AI) | 90.3% | Not measured | Only Claude Opus 5.5 measured |
| Code migration (Vals AI) | 66.7% | Not measured | Only Claude Opus 5.5 measured |
| ProgramBench (Vals AI) | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| IOI (Vals AI) | 95.1% | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 87.6% | Not measured | Only Claude Opus 5.5 measured |
| SWE-bench Multimodal (Vals AI) | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| Vibe Code Bench 1-100 (Vals AI) | 30.4% | Not measured | Only Claude Opus 5.5 measured |
| CyberBench (Vals AI) | 74.6% | Not measured | Only Claude Opus 5.5 measured |
| LiveCodeBench (Artificial Analysis run) | Not measured | 69.5% | Only Gemini 2.5 Flash measured |
| SciCode | 66.9% | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 13.6% | Only Gemini 2.5 Flash measured |
| Terminal-Bench | Not measured | 17.1% | Only Gemini 2.5 Flash measured |
| FrontierCode | 54.6% | Not measured | Only Claude Opus 5.5 measured |
| FrontierSWE | 62.3% | Not measured | Only Claude Opus 5.5 measured |
| MirrorCode | 77.4% | Not measured | Only Claude Opus 5.5 measured |
| ALE-Bench | 2147.4 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: coding | 1545 | 1423 | Claude Opus 5.5 |
| LMArena Text: software and IT | 1538 | 1425 | Claude Opus 5.5 |
| LMArena WebDev: React | 1855 | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev: HTML | 1753 | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev: from an image | 1753 | Not measured | Only Claude Opus 5.5 measured |
| SciCode | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 13 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| AA Intelligence Index | 57.6 | 15.5 | Claude Opus 5.5 |
| Epoch Capabilities Index | 168.8 | 142.9 | Claude Opus 5.5 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1316 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: agents building mobile apps | 1308 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: spreadsheets | 1368 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench research | 85.0% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench browser | 80.0% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench long agentic | 85.0% | Not measured | Only Claude Opus 5.5 measured |
| SREBench (Vals AI) | 33.6% | Not measured | Only Claude Opus 5.5 measured |
| Finance Agent (Vals AI) | 58.6% | Not measured | Only Claude Opus 5.5 measured |
| Tax Agent Bench (Vals AI) | 45.6% | Not measured | Only Claude Opus 5.5 measured |
| Legal Research Bench (Vals AI) | 50.5% | Not measured | Only Claude Opus 5.5 measured |
| Harvey's Legal Agent Benchmark (Vals AI) | 9.2% | Not measured | Only Claude Opus 5.5 measured |
| Excel Modeling Benchmark (Vals AI) | 75.9% | Not measured | Only Claude Opus 5.5 measured |
| BioMysteryBench (Vals AI) | 79.3% | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench-Science (Vals AI) | 47.1% | Not measured | Only Claude Opus 5.5 measured |
| Vals Science Index | 58.7% | Not measured | Only Claude Opus 5.5 measured |
| Time Horizon Index (Vals AI) | 91.3% | Not measured | Only Claude Opus 5.5 measured |
| CUA-bench (Vals AI) | 14.0% | Not measured | Only Claude Opus 5.5 measured |
| Robo-bench (Vals AI) | 14.6% | Not measured | Only Claude Opus 5.5 measured |
| τ²-Bench Telecom | Not measured | 31.6% | Only Gemini 2.5 Flash measured |
| APEX-Agents | 73.5% | Not measured | Only Claude Opus 5.5 measured |
| Remote Labor Index | 21.3% | Not measured | Only Claude Opus 5.5 measured |
| BALROG | Not measured | 33.5% | Only Gemini 2.5 Flash measured |
| SpireClimb | 3.3% | Not measured | Only Claude Opus 5.5 measured |
| Vending-Bench 2 | $9,235 | $549 | Claude Opus 5.5 |
| LMArena Search | 1213 | Not measured | Only Claude Opus 5.5 measured |
| Berkeley Function Calling Leaderboard (BFCL) | Not measured | 56.2% | Only Gemini 2.5 Flash measured |
| BrowseComp-Plus | Not measured | 39.9% | Only Gemini 2.5 Flash measured |
| Neither model has a result on the other 14 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index80
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| LiveBench reasoning | 92.2% | Not measured | Only Claude Opus 5.5 measured |
| MysteryMechanism (Vals AI) | 49.5% | Not measured | Only Claude Opus 5.5 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 79.0% | Only Gemini 2.5 Flash measured |
| Humanity's Last Exam (Artificial Analysis run) | 61.4% | 12.1% | Claude Opus 5.5 |
| GPQA Diamond (Epoch AI run) | 90.6% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI | 98.5% | 33.3% | Claude Opus 5.5 |
| ARC-AGI-2 | 93.3% | 2.5% | Claude Opus 5.5 |
| SimpleBench | Not measured | 41.2% | Only Gemini 2.5 Flash measured |
| Chess puzzles | 67.0% | Not measured | Only Claude Opus 5.5 measured |
| Mystery game puzzles | 71.0% | Not measured | Only Claude Opus 5.5 measured |
| EBR-bench | 71.4% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: hard prompts | 1536 | 1422 | Claude Opus 5.5 |
| LMArena Text: expert | 1549 | 1426 | Claude Opus 5.5 |
| LMArena Text: hard prompts in English | 1535 | 1420 | Claude Opus 5.5 |
| LMArena Vision: diagrams | 1345 | 1245 | Claude Opus 5.5 |
| LMArena Vision: homework | 1362 | 1244 | Claude Opus 5.5 |
| Kagi LLM Benchmark | Not measured | 56.8% | Only Gemini 2.5 Flash measured |
| Neither model has a result on the other 5 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| AA Math Index | Not measured | 73.3 | Only Gemini 2.5 Flash measured |
| AIME 2025 (Artificial Analysis run) | Not measured | 73.3% | Only Gemini 2.5 Flash measured |
| OTIS Mock AIME | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tiers 1 to 3 | 91.2% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tier 4 | 95.0% | Not measured | Only Claude Opus 5.5 measured |
| ProofBench | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: math | 1518 | 1411 | Claude Opus 5.5 |
| LMArena Text: mathematical work | 1516 | 1422 | Claude Opus 5.5 |
| Neither model has a result on the other 5 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index60
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| MedCode (Vals AI) | 49.8% | 40.4% | Claude Opus 5.5 |
| MMLU Pro (Artificial Analysis run) | Not measured | 83.2% | Only Gemini 2.5 Flash measured |
| SimpleQA Verified | 72.2% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: science | 1524 | 1433 | Claude Opus 5.5 |
| LMArena Text: medicine and healthcare | 1509 | 1428 | Claude Opus 5.5 |
| LMArena Text: legal and government | 1518 | 1430 | Claude Opus 5.5 |
| LMArena Text: business and finance | 1494 | 1404 | Claude Opus 5.5 |
| FACTS Benchmark Suite | 65.3% | 47.2% | Claude Opus 5.5 |
| Neither model has a result on the other 10 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| Design Arena: websites | 1335 | 1074 | Claude Opus 5.5 |
| Design Arena: UI components | 1385 | 1002 | Claude Opus 5.5 |
| Design Arena: game dev | 1461 | 1004 | Claude Opus 5.5 |
| Design Arena: data viz | 1397 | 1060 | Claude Opus 5.5 |
| Design Arena: 3D | 1476 | 1020 | Claude Opus 5.5 |
| Design Arena: all code categories | 1390 | 1059 | Claude Opus 5.5 |
| Design Arena: SVG | 1329 | 1020 | Claude Opus 5.5 |
| LiveBench design | 86.9% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index230
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| Vals Index | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench data analysis | 80.3% | Not measured | Only Claude Opus 5.5 measured |
| Public Benefits Bench (Vals AI) | 70.6% | Not measured | Only Claude Opus 5.5 measured |
| SAGE (Vals AI) | 45.8% | 44.8% | Claude Opus 5.5 |
| MedScribe (Vals AI) | 91.4% | 83.0% | Claude Opus 5.5 |
| IFBench | Not measured | 50.3% | Only Gemini 2.5 Flash measured |
| Long context reasoning (AA-LCR) | 84.7% | 65.3% | Claude Opus 5.5 |
| DTBench | 98.9% | 76.5% | Claude Opus 5.5 |
| LMCA | 68.2% | 27.5% | Claude Opus 5.5 |
| Furniture assembly | 83.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text | 1516 | 1417 | Claude Opus 5.5 |
| LMArena Text: instruction following | 1537 | 1405 | Claude Opus 5.5 |
| LMArena Text: creative writing | 1535 | 1400 | Claude Opus 5.5 |
| LMArena Vision | 1321 | 1235 | Claude Opus 5.5 |
| LMArena Text: English | 1519 | 1418 | Claude Opus 5.5 |
| LMArena Text: non-English | 1507 | 1409 | Claude Opus 5.5 |
| LMArena Text: Chinese | 1582 | 1449 | Claude Opus 5.5 |
| LMArena Text: German | Not measured | 1417 | Only Gemini 2.5 Flash measured |
| LMArena Text: Japanese | 1534 | 1396 | Claude Opus 5.5 |
| LMArena Text: Korean | Not measured | 1385 | Only Gemini 2.5 Flash measured |
| LMArena Text: French | 1493 | 1432 | Claude Opus 5.5 |
| LMArena Text: Spanish | 1508 | 1422 | Claude Opus 5.5 |
| LMArena Text: Russian | 1517 | 1415 | Claude Opus 5.5 |
| LMArena Text: Polish | Not measured | 1413 | Only Gemini 2.5 Flash measured |
| LMArena Text: multi-turn | 1501 | 1408 | Claude Opus 5.5 |
| LMArena Text: longer queries | 1532 | 1419 | Claude Opus 5.5 |
| LMArena Text: writing and language | 1532 | 1405 | Claude Opus 5.5 |
| LMArena Text: entertainment and media | 1515 | 1393 | Claude Opus 5.5 |
| LMArena Vision: English | 1317 | 1239 | Claude Opus 5.5 |
| LMArena Vision: Chinese | Not measured | 1284 | Only Gemini 2.5 Flash measured |
| LMArena Vision: reading text | 1326 | 1237 | Claude Opus 5.5 |
| LMArena Vision: humor | Not measured | 1225 | Only Gemini 2.5 Flash measured |
| LMArena Vision: captioning | Not measured | 1277 | Only Gemini 2.5 Flash measured |
| LMArena Vision: recognizing things | Not measured | 1252 | Only Gemini 2.5 Flash measured |
| LMArena Vision: creative writing | 1320 | 1241 | Claude Opus 5.5 |
| Neither model has a result on the other 11 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 5.5 | Gemini 2.5 Flash | 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 Opus 5.5$0.014Fits in one request
Gemini 2.5 Flash$0.0015Fits in one request
Gemini 2.5 Flash costs less
Repository review
50K input + 3K output tokens
Claude Opus 5.5$0.260Fits in one request
Gemini 2.5 Flash$0.022Fits in one request
Gemini 2.5 Flash costs less
Agent loop
200K input + 10K output tokens
Claude Opus 5.5$1.00Fits in one request
Gemini 2.5 Flash$0.085Fits in one request
Gemini 2.5 Flash 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 Opus 5.5 | Google Gemini 2.5 Flash |
|---|---|---|
| Maker | Anthropic | |
| Weights | No public weights listed | No public weights listed |
| Released | September 22, 2026 | June 17, 2025 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $4.00 | $0.30 |
| Output $/Mtok | $20.00 | $2.50 |
| Coding index | 88.8 | Not benchmarked |
| Independent measurements behind it | 5 | 0 |
| Cost per solved task | Not computable | $0.466 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 5.5 better than Gemini 2.5 Flash for coding?
Only Claude Opus 5.5 has a coding score, 88.8 on the Vibe Coding Index; Gemini 2.5 Flash has none, so the two cannot be ranked on coding. Pick Gemini 2.5 Flash for output tokens 8.0x cheaper ($2.50 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
Which is cheaper, Claude Opus 5.5 or Gemini 2.5 Flash?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Gemini 2.5 Flash costs $0.30 and $2.50. Cost per solved task is known for Gemini 2.5 Flash only.
Which has the bigger context window, Claude Opus 5.5 or Gemini 2.5 Flash?
Gemini 2.5 Flash, with 1.05M tokens against 1M.
How many benchmarks is the Claude Opus 5.5 vs Gemini 2.5 Flash comparison based on?
51 benchmarks have a result for both models as of October 22, 2026. Claude Opus 5.5's coding index rests on 5 independent benchmarks and Gemini 2.5 Flash's on 0. Where only one model has a result, the page says so instead of naming a winner.