Claude Sonnet 5.5 vs o1
Updated October 21, 2026. 37 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 37 shared
Decision reading
Pick Claude Sonnet 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 61.7 for o1.
o1 is neither cheaper nor larger in context, and leads no benchmark both models were measured on.
Model AClaude Sonnet 5.5Anthropic88.9/1002 independent benchmarksNo cost per solved taskModel Bo1OpenAI61.7/1001 independent benchmarkNo cost per solved task
- Shared results
- 37
- Claude Sonnet 5.5 only
- 58
- o1 only
- 31
- Like-for-like categories
- 6 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 61.7.
2 and 1 benchmarks behind the scores
Intelligence
AA Intelligence Index
Claude Sonnet 5.5
Claude Sonnet 5.5 leads, 56.0 against 15.2.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only o1 has a GPQA Diamond result, 73.2%.
Directional only
Math
AIME
No call
Only o1 has a AIME result, 71.5%.
Directional only
Knowledge
MMLU Pro
No call
Only o1 has a MMLU Pro result, 83.5%.
Directional only
Web design
Design Arena: websites
No call
Only Claude Sonnet 5.5 has a Design Arena: websites result, 1326.
Directional only
General
Vals Index
No call
Only Claude Sonnet 5.5 has a Vals Index result, 70.8%.
Directional only
Long documents
Listed context window
Claude Sonnet 5.5
Claude Sonnet 5.5 takes 1M tokens against 200K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Claude Sonnet 5.5
Claude Sonnet 5.5 $0.0070, o1 $0.045 per turn.
List prices
At a glance
- Coding index
- Claude Sonnet 5.5 88.9 from 2 benchmarks, o1 61.7 from 1 benchmark.
- Widest category
- Intelligence, 35.7 points apart on average over 2 shared benchmarks.
- Widest single gap
- FrontierMath, tiers 1 to 3: Claude Sonnet 5.5 88.8% against o1 14.7%, 74.0 points apart on a 0 to 100 scale.
- Output price
- Claude Sonnet 5.5 $10.00 against o1 $60.00 per million output tokens, 6.0x apart.
- Context window
- Claude Sonnet 5.5 takes 1M tokens, o1 200K.
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 | o1 | Ties |
|---|---|---|---|---|
| Coding | 2 | 0 | ||
| Intelligence | 2 | 0 | ||
| Reasoning | 6 | 0 | ||
| Math | 4 | 0 | ||
| Knowledge | 5 | 0 | ||
| General | 18 | 0 | ||
| All shared boards | 37 | 0 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index20
| Benchmark | Claude Sonnet 5.5 | o1 | Leader |
|---|---|---|---|
| Aider polyglot | Not measured | 61.7% | Only o1 measured |
| LiveBench coding | 94.7% | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena WebDev | 1768 | Not measured | Only Claude Sonnet 5.5 measured |
| AA Coding Index | Not measured | 39.7 | Only o1 measured |
| LiveCodeBench (Vals AI) | Not measured | 50.3% | Only o1 measured |
| Terminal-Bench 4 (Vals AI) | 64.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Vibe Code Bench (Vals AI) | 92.4% | Not measured | Only Claude Sonnet 5.5 measured |
| Code migration (Vals AI) | 69.8% | Not measured | Only Claude Sonnet 5.5 measured |
| ProgramBench (Vals AI) | 6.5% | Not measured | Only Claude Sonnet 5.5 measured |
| IOI (Vals AI) | 83.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 83.2% | Not measured | Only Claude Sonnet 5.5 measured |
| 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 | 67.9% | Only o1 measured |
| SciCode | 61.0% | Not measured | Only Claude Sonnet 5.5 measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 12.9% | Only o1 measured |
| FrontierCode | 52.1% | Not measured | Only Claude Sonnet 5.5 measured |
| FrontierSWE | 61.9% | Not measured | Only Claude Sonnet 5.5 measured |
| WeirdML | Not measured | 46.1% | Only o1 measured |
| ALE-Bench | 1819.1 | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text: coding | 1513 | 1367 | Claude Sonnet 5.5 |
| LMArena Text: software and IT | 1504 | 1366 | Claude Sonnet 5.5 |
| 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 13 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Sonnet 5.5 | o1 | Leader |
|---|---|---|---|
| AA Intelligence Index | 56.0 | 15.2 | Claude Sonnet 5.5 |
| Epoch Capabilities Index | 166.2 | 141.7 | Claude Sonnet 5.5 |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index20 boards, none shared
| Benchmark | Claude Sonnet 5.5 | o1 | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1303 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: agents building mobile apps | 1265 | Not measured | Only Claude Sonnet 5.5 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% | Not measured | Only Claude Sonnet 5.5 measured |
| Tax Agent Bench (Vals AI) | 42.0% | Not measured | Only Claude Sonnet 5.5 measured |
| Legal Research Bench (Vals AI) | 48.1% | Not measured | Only Claude Sonnet 5.5 measured |
| Harvey's Legal Agent Benchmark (Vals AI) | 10.4% | Not measured | Only Claude Sonnet 5.5 measured |
| Excel Modeling Benchmark (Vals AI) | 75.7% | Not measured | Only Claude Sonnet 5.5 measured |
| 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 | 62.6% | Only o1 measured |
| APEX-Agents | 75.5% | Not measured | Only Claude Sonnet 5.5 measured |
| METR time horizons | Not measured | 51.1% | Only o1 measured |
| SpireClimb | 1.3% | Not measured | Only Claude Sonnet 5.5 measured |
| Vending-Bench 2 | $11,165 | Not measured | Only Claude Sonnet 5.5 measured |
| Neither model has a result on the other 19 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index60
| Benchmark | Claude Sonnet 5.5 | o1 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 73.2% | Only o1 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 | 77.4% | Only o1 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 74.7% | Only o1 measured |
| Humanity's Last Exam (Artificial Analysis run) | 55.0% | 7.0% | Claude Sonnet 5.5 |
| GPQA Diamond (Epoch AI run) | 95.6% | 76.8% | Claude Sonnet 5.5 |
| ARC-AGI | Not measured | 30.7% | Only o1 measured |
| SimpleBench | Not measured | 40.1% | Only o1 measured |
| Chess puzzles | 59.0% | 10.0% | Claude Sonnet 5.5 |
| Mystery game puzzles | 65.0% | Not measured | Only Claude Sonnet 5.5 measured |
| VPCT | Not measured | 37.0% | Only o1 measured |
| LMArena Text: hard prompts | 1494 | 1371 | Claude Sonnet 5.5 |
| LMArena Text: expert | 1531 | 1361 | Claude Sonnet 5.5 |
| LMArena Text: hard prompts in English | 1502 | 1372 | Claude Sonnet 5.5 |
| 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 4 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Sonnet 5.5 | o1 | Leader |
|---|---|---|---|
| AIME | Not measured | 71.5% | Only o1 measured |
| MATH 500 (Vals AI) | Not measured | 90.4% | Only o1 measured |
| MGSM (Vals AI) | Not measured | 89.3% | Only o1 measured |
| OTIS Mock AIME | 100.0% | 73.3% | Claude Sonnet 5.5 |
| FrontierMath, tiers 1 to 3 | 88.8% | 14.7% | Claude Sonnet 5.5 |
| FrontierMath, tier 4 | 80.5% | Not measured | Only Claude Sonnet 5.5 measured |
| ProofBench | 100.0% | Not measured | Only Claude Sonnet 5.5 measured |
| MATH level 5 | Not measured | 94.7% | Only o1 measured |
| LMArena Text: math | 1497 | 1388 | Claude Sonnet 5.5 |
| LMArena Text: mathematical work | 1510 | 1390 | Claude Sonnet 5.5 |
| Neither model has a result on the other 3 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index50
| Benchmark | Claude Sonnet 5.5 | o1 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 83.5% | Only o1 measured |
| LegalBench (Vals AI) | Not measured | 80.4% | Only o1 measured |
| TaxEval (Vals AI) | Not measured | 74.3% | Only o1 measured |
| MedQA (Vals AI) | Not measured | 96.5% | Only o1 measured |
| MedCode (Vals AI) | 52.9% | Not measured | Only Claude Sonnet 5.5 measured |
| MMLU Pro (Artificial Analysis run) | Not measured | 84.1% | Only o1 measured |
| SimpleQA Verified | 46.5% | 41.1% | Claude Sonnet 5.5 |
| GeoBench | Not measured | 80.0% | Only o1 measured |
| LMArena Text: science | 1483 | 1369 | Claude Sonnet 5.5 |
| LMArena Text: medicine and healthcare | 1464 | 1355 | Claude Sonnet 5.5 |
| LMArena Text: legal and government | 1483 | 1368 | Claude Sonnet 5.5 |
| LMArena Text: business and finance | 1468 | 1328 | Claude Sonnet 5.5 |
| Neither model has a result on the other 5 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index7 boards, none shared
| Benchmark | Claude Sonnet 5.5 | o1 | Leader |
|---|---|---|---|
| Design Arena: websites | 1326 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: UI components | 1367 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: game dev | 1469 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: data viz | 1389 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: 3D | 1458 | Not measured | Only Claude Sonnet 5.5 measured |
| Design Arena: all code categories | 1364 | Not measured | Only Claude Sonnet 5.5 measured |
| 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 index180
| Benchmark | Claude Sonnet 5.5 | o1 | 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% | Not measured | Only Claude Sonnet 5.5 measured |
| MedScribe (Vals AI) | 91.1% | Not measured | Only Claude Sonnet 5.5 measured |
| IFBench | Not measured | 70.3% | Only o1 measured |
| Long context reasoning (AA-LCR) | 82.7% | 65.0% | Claude Sonnet 5.5 |
| DTBench | 97.3% | 74.7% | Claude Sonnet 5.5 |
| LMCA | 68.3% | 22.3% | Claude Sonnet 5.5 |
| Fiction.LiveBench | Not measured | 83.3% | Only o1 measured |
| Creative writing (Lech Mazur) | Not measured | 70.2% | Only o1 measured |
| Furniture assembly | 75.0% | Not measured | Only Claude Sonnet 5.5 measured |
| LMArena Text | 1473 | 1366 | Claude Sonnet 5.5 |
| LMArena Text: instruction following | 1492 | 1367 | Claude Sonnet 5.5 |
| LMArena Text: creative writing | 1467 | 1347 | Claude Sonnet 5.5 |
| LMArena Vision | 1287 | 1168 | Claude Sonnet 5.5 |
| LMArena Text: English | 1484 | 1372 | Claude Sonnet 5.5 |
| LMArena Text: non-English | 1456 | 1358 | Claude Sonnet 5.5 |
| LMArena Text: Chinese | 1535 | 1394 | Claude Sonnet 5.5 |
| LMArena Text: German | Not measured | 1337 | Only o1 measured |
| LMArena Text: Japanese | Not measured | 1346 | Only o1 measured |
| LMArena Text: Korean | Not measured | 1396 | Only o1 measured |
| LMArena Text: French | 1499 | 1344 | Claude Sonnet 5.5 |
| LMArena Text: Spanish | 1451 | 1345 | Claude Sonnet 5.5 |
| LMArena Text: Russian | 1454 | 1356 | Claude Sonnet 5.5 |
| LMArena Text: multi-turn | 1465 | 1355 | Claude Sonnet 5.5 |
| LMArena Text: longer queries | 1495 | 1378 | Claude Sonnet 5.5 |
| LMArena Text: writing and language | 1474 | 1360 | Claude Sonnet 5.5 |
| LMArena Text: entertainment and media | 1461 | 1358 | Claude Sonnet 5.5 |
| LMArena Vision: English | 1289 | 1162 | Claude Sonnet 5.5 |
| LMArena Vision: Chinese | Not measured | 1235 | Only o1 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 13 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Sonnet 5.5 | o1 | 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
o1$0.045Fits in one request
Claude Sonnet 5.5 costs less
Repository review
50K input + 3K output tokens
Claude Sonnet 5.5$0.130Fits in one request
o1$0.930Fits in one request
Claude Sonnet 5.5 costs less
Agent loop
200K input + 10K output tokens
Claude Sonnet 5.5$0.500Fits in one request
o1$3.60Exceeds the context window
Claude Sonnet 5.5 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 | OpenAI o1 |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | September 28, 2026 | December 17, 2024 |
| Context window | 1M | 200K |
| Input $/Mtok | $2.00 | $15.00 |
| Output $/Mtok | $10.00 | $60.00 |
| Coding index | 88.9 | 61.7 |
| Independent measurements behind it | 2 | 1 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Sonnet 5.5 better than o1 for coding?
Pick Claude Sonnet 5.5 for coding: it scores 88.9 on the Vibe Coding Index against 61.7 for o1. o1 is neither cheaper nor larger in context, and leads no benchmark both models were measured on.
Which is cheaper, Claude Sonnet 5.5 or o1?
Claude Sonnet 5.5 costs $2.00 per million input tokens and $10.00 per million output tokens; o1 costs $15.00 and $60.00. Cost per solved task is known for neither of them.
Which has the bigger context window, Claude Sonnet 5.5 or o1?
Claude Sonnet 5.5, with 1M tokens against 200K.
How many benchmarks is the Claude Sonnet 5.5 vs o1 comparison based on?
37 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 o1's on 1. Where only one model has a result, the page says so instead of naming a winner.