Claude Opus 5.5 vs Step 5 Preview
Claude Opus 5.5 leads Step 5 Preview on coding, 88.8 to 61.1 on the Vibe Coding Index, and Step 5 Preview costs 7.4x less per output token ($2.70 vs $20.00 per million). Updated October 22, 2026; 61 benchmarks have a result for both.
Claude Opus 5.5 or Step 5 Preview: which to pick
Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 61.1 for Step 5 Preview.
Pick Step 5 Preview for output tokens 7.4x cheaper ($2.70 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
- Shared results
- 61
- Claude Opus 5.5 only
- 48
- Step 5 Preview only
- 0
- 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
Claude Opus 5.5
Claude Opus 5.5 scores 88.8 against 61.1.
5 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
Claude Opus 5.5
Claude Opus 5.5 leads, 57.6 against 43.7.
Same board, both measured
Web design
Design Arena: websites
No call
Only Claude Opus 5.5 has a Design Arena: websites result, 1335.
Directional only
General
Vals Index
No call
Only Claude Opus 5.5 has a Vals Index result, 70.2%.
Directional only
Long documents
Listed context window
Step 5 Preview
Step 5 Preview takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Step 5 Preview
Claude Opus 5.5 $0.014, Step 5 Preview $0.0024 per turn.
List prices
At a glance
- Coding index
- Claude Opus 5.5 88.8 from 5 benchmarks, Step 5 Preview 61.1 from 4 benchmarks.
- Widest category
- Agentic work, 27.2 points apart on average over 11 shared benchmarks.
- Widest single gap
- ProofBench: Claude Opus 5.5 100.0% against Step 5 Preview 42.0%, 58.0 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 5.5 $20.00 against Step 5 Preview $2.70 per million output tokens, 7.4x apart.
- Context window
- Claude Opus 5.5 takes 1M tokens, Step 5 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 Opus 5.5 | Bars | Step 5 Preview | Ties |
|---|---|---|---|---|
| Coding | 13 | 0 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 11 | 0 | ||
| Reasoning | 8 | 0 | ||
| Math | 3 | 0 | ||
| Knowledge | 4 | 0 | ||
| Web design | 1 | 0 | ||
| General | 19 | 1 | ||
| All shared boards | 60 | 1 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index130
| Benchmark | Claude Opus 5.5 | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench coding | 96.3% | 85.6% | Claude Opus 5.5 |
| LMArena WebDev | 1807 | 1567 | Claude Opus 5.5 |
| Terminal-Bench 4 (Vals AI) | 65.2% | 31.8% | Claude Opus 5.5 |
| Vibe Code Bench (Vals AI) | 90.3% | 70.4% | Claude Opus 5.5 |
| Code migration (Vals AI) | 66.7% | 39.0% | Claude Opus 5.5 |
| ProgramBench (Vals AI) | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| IOI (Vals AI) | 95.1% | 38.1% | Claude Opus 5.5 |
| Terminal-Bench 2.1 (Vals AI) | 87.6% | Not measured | Only Claude Opus 5.5 measured |
| SWE-bench Multimodal (Vals AI) | 70.2% | 40.8% | Claude Opus 5.5 |
| 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 |
| SciCode | 66.9% | 58.9% | Claude Opus 5.5 |
| 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 | 1485 | Claude Opus 5.5 |
| LMArena Text: software and IT | 1538 | 1473 | Claude Opus 5.5 |
| LMArena WebDev: React | 1855 | 1583 | Claude Opus 5.5 |
| LMArena WebDev: HTML | 1753 | 1556 | Claude Opus 5.5 |
| LMArena WebDev: from an image | 1753 | 1550 | Claude Opus 5.5 |
| SciCode | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 17 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 5.5 | Step 5 Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | 57.6 | 43.7 | Claude Opus 5.5 |
| Epoch Capabilities Index | 168.8 | Not measured | Only Claude Opus 5.5 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index110
| Benchmark | Claude Opus 5.5 | Step 5 Preview | 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% | 72.8% | Claude Opus 5.5 |
| LiveBench browser | 80.0% | 24.0% | Claude Opus 5.5 |
| LiveBench long agentic | 85.0% | 27.5% | Claude Opus 5.5 |
| SREBench (Vals AI) | 33.6% | 0.4% | Claude Opus 5.5 |
| Finance Agent (Vals AI) | 58.6% | 50.7% | Claude Opus 5.5 |
| Tax Agent Bench (Vals AI) | 45.6% | 27.3% | Claude Opus 5.5 |
| Legal Research Bench (Vals AI) | 50.5% | 40.4% | Claude Opus 5.5 |
| Harvey's Legal Agent Benchmark (Vals AI) | 9.2% | Not measured | Only Claude Opus 5.5 measured |
| Excel Modeling Benchmark (Vals AI) | 75.9% | 57.1% | Claude Opus 5.5 |
| BioMysteryBench (Vals AI) | 79.3% | 67.4% | Claude Opus 5.5 |
| Terminal-Bench-Science (Vals AI) | 47.1% | 2.9% | Claude Opus 5.5 |
| Vals Science Index | 58.7% | 29.6% | Claude Opus 5.5 |
| 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 |
| 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 |
| SpireClimb | 3.3% | Not measured | Only Claude Opus 5.5 measured |
| Vending-Bench 2 | $9,235 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Search | 1213 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 18 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index80
| Benchmark | Claude Opus 5.5 | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench reasoning | 92.2% | 83.8% | Claude Opus 5.5 |
| MysteryMechanism (Vals AI) | 49.5% | 18.5% | Claude Opus 5.5 |
| Humanity's Last Exam (Artificial Analysis run) | 61.4% | 46.5% | Claude Opus 5.5 |
| GPQA Diamond (Epoch AI run) | 90.6% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI | 98.5% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI-2 | 93.3% | Not measured | Only Claude Opus 5.5 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 | 1461 | Claude Opus 5.5 |
| LMArena Text: expert | 1549 | 1485 | Claude Opus 5.5 |
| LMArena Text: hard prompts in English | 1535 | 1454 | Claude Opus 5.5 |
| LMArena Vision: diagrams | 1345 | 1308 | Claude Opus 5.5 |
| LMArena Vision: homework | 1362 | 1265 | Claude Opus 5.5 |
| Neither model has a result on the other 8 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Opus 5.5 | Step 5 Preview | Leader |
|---|---|---|---|
| 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% | 42.0% | Claude Opus 5.5 |
| LMArena Text: math | 1518 | 1458 | Claude Opus 5.5 |
| LMArena Text: mathematical work | 1516 | 1460 | Claude Opus 5.5 |
| Neither model has a result on the other 7 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Opus 5.5 | Step 5 Preview | Leader |
|---|---|---|---|
| MedCode (Vals AI) | 49.8% | Not measured | Only Claude Opus 5.5 measured |
| SimpleQA Verified | 72.2% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: science | 1524 | 1454 | Claude Opus 5.5 |
| LMArena Text: medicine and healthcare | 1509 | 1439 | Claude Opus 5.5 |
| LMArena Text: legal and government | 1518 | 1437 | Claude Opus 5.5 |
| LMArena Text: business and finance | 1494 | 1435 | Claude Opus 5.5 |
| FACTS Benchmark Suite | 65.3% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 11 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 5.5 | Step 5 Preview | Leader |
|---|---|---|---|
| Design Arena: websites | 1335 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: UI components | 1385 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: game dev | 1461 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: data viz | 1397 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: 3D | 1476 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: all code categories | 1390 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: SVG | 1329 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench design | 86.9% | 76.9% | Claude Opus 5.5 |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index191
| Benchmark | Claude Opus 5.5 | Step 5 Preview | Leader |
|---|---|---|---|
| Vals Index | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench data analysis | 80.3% | 63.5% | Claude Opus 5.5 |
| Public Benefits Bench (Vals AI) | 70.6% | 58.1% | Claude Opus 5.5 |
| SAGE (Vals AI) | 45.8% | Not measured | Only Claude Opus 5.5 measured |
| MedScribe (Vals AI) | 91.4% | Not measured | Only Claude Opus 5.5 measured |
| Long context reasoning (AA-LCR) | 84.7% | 88.3% | Step 5 Preview |
| DTBench | 98.9% | Not measured | Only Claude Opus 5.5 measured |
| LMCA | 68.2% | Not measured | Only Claude Opus 5.5 measured |
| Furniture assembly | 83.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text | 1516 | 1440 | Claude Opus 5.5 |
| LMArena Text: instruction following | 1537 | 1438 | Claude Opus 5.5 |
| LMArena Text: creative writing | 1535 | 1409 | Claude Opus 5.5 |
| LMArena Vision | 1321 | 1265 | Claude Opus 5.5 |
| LMArena Text: English | 1519 | 1447 | Claude Opus 5.5 |
| LMArena Text: non-English | 1507 | 1428 | Claude Opus 5.5 |
| LMArena Text: Chinese | 1582 | 1500 | Claude Opus 5.5 |
| LMArena Text: Japanese | 1534 | 1383 | Claude Opus 5.5 |
| LMArena Text: French | 1493 | 1438 | Claude Opus 5.5 |
| LMArena Text: Spanish | 1508 | 1441 | Claude Opus 5.5 |
| LMArena Text: Russian | 1517 | 1433 | Claude Opus 5.5 |
| LMArena Text: multi-turn | 1501 | 1437 | Claude Opus 5.5 |
| LMArena Text: longer queries | 1532 | 1449 | Claude Opus 5.5 |
| LMArena Text: writing and language | 1532 | 1425 | Claude Opus 5.5 |
| LMArena Text: entertainment and media | 1515 | 1412 | Claude Opus 5.5 |
| LMArena Vision: English | 1317 | 1290 | Claude Opus 5.5 |
| LMArena Vision: reading text | 1326 | 1282 | Claude Opus 5.5 |
| LMArena Vision: creative writing | 1320 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 19 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 5.5 | Step 5 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
Step 5 Preview costs less
Repository review
50K input + 3K output tokens
Step 5 Preview costs less
Agent loop
200K input + 10K output tokens
Step 5 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 Opus 5.5 | StepFun Step 5 Preview |
|---|---|---|
| Maker | Anthropic | StepFun |
| Weights | No public weights listed | Open weights |
| Released | September 22, 2026 | October 8, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $4.00 | $1.00 |
| Output $/Mtok | $20.00 | $2.70 |
| Coding index | 88.8 | 61.1 |
| Independent measurements behind it | 5 | 4 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 5.5 better than Step 5 Preview for coding?
Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 61.1 for Step 5 Preview. Pick Step 5 Preview for output tokens 7.4x cheaper ($2.70 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).
Which is cheaper, Claude Opus 5.5 or Step 5 Preview?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Step 5 Preview costs $1.00 and $2.70. Cost per solved task is known for neither of them.
Which has the bigger context window, Claude Opus 5.5 or Step 5 Preview?
Step 5 Preview, with 1.05M tokens against 1M.
How many benchmarks is the Claude Opus 5.5 vs Step 5 Preview comparison based on?
61 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 Step 5 Preview's on 4. Where only one model has a result, the page says so instead of naming a winner.