Claude Sonnet 5 vs Step 5 Preview
Step 5 Preview leads Claude Sonnet 5 on coding, 61.1 to 57.7 on the Vibe Coding Index, and Step 5 Preview costs 3.7x less per output token ($2.70 vs $10.00 per million). Updated October 21, 2026; 57 benchmarks have a result for both.
Claude Sonnet 5 or Step 5 Preview: which to pick
Pick Step 5 Preview for coding: it scores 61.1 on the Vibe Coding Index against 57.7 for Claude Sonnet 5, though on 4 benchmarks against 6.
Pick Claude Sonnet 5 for work measured by Vibe Code Bench (Vals AI) or Code migration (Vals AI), where it leads.
- Shared results
- 57
- Claude Sonnet 5 only
- 64
- Step 5 Preview only
- 4
- 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
Step 5 Preview
Step 5 Preview scores 61.1 against 57.7.
6 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
Step 5 Preview
Step 5 Preview leads, 43.7 against 38.2.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Claude Sonnet 5 has a AA Agentic Index result, 43.6.
Directional only
Reasoning
GPQA Diamond
No call
Only Claude Sonnet 5 has a GPQA Diamond result, 88.9%.
Directional only
Knowledge
MMLU Pro
No call
Only Claude Sonnet 5 has a MMLU Pro result, 87.5%.
Directional only
Web design
Design Arena: websites
No call
Only Claude Sonnet 5 has a Design Arena: websites result, 1274.
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 Sonnet 5 $0.0070, Step 5 Preview $0.0024 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Claude Sonnet 5 has the number, $1.87.
Directional only
At a glance
- Coding index
- Claude Sonnet 5 57.7 from 6 benchmarks, Step 5 Preview 61.1 from 4 benchmarks.
- Widest category
- Math, 13.4 points apart on average over 3 shared benchmarks.
- Widest single gap
- LiveBench browser: Claude Sonnet 5 72.0% against Step 5 Preview 24.0%, 48.0 points apart on a 0 to 100 scale.
- Output price
- Claude Sonnet 5 $10.00 against Step 5 Preview $2.70 per million output tokens, 3.7x apart.
- Context window
- Claude Sonnet 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 Sonnet 5 | Bars | Step 5 Preview | Ties |
|---|---|---|---|---|
| Coding | 4 | 8 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 8 | 0 | 1 tie | |
| Reasoning | 4 | 3 | ||
| Math | 3 | 0 | ||
| Knowledge | 4 | 0 | ||
| Web design | 1 | 0 | ||
| General | 15 | 5 | ||
| All shared boards | 39 | 17 | 1 tie |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index48
| Benchmark | Claude Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench coding | 74.7% | 85.6% | Step 5 Preview |
| LMArena WebDev | 1540 | 1567 | Step 5 Preview |
| AA Coding Index | 71.5 | Not measured | Only Claude Sonnet 5 measured |
| LiveCodeBench (Vals AI) | 82.4% | Not measured | Only Claude Sonnet 5 measured |
| SWE-bench Verified (Vals AI) | 79.6% | Not measured | Only Claude Sonnet 5 measured |
| Terminal-Bench 4 (Vals AI) | 10.6% | 31.8% | Step 5 Preview |
| Vibe Code Bench (Vals AI) | 81.3% | 70.4% | Claude Sonnet 5 |
| Code migration (Vals AI) | 44.4% | 39.0% | Claude Sonnet 5 |
| ProgramBench (Vals AI) | 0.0% | Not measured | Only Claude Sonnet 5 measured |
| IOI (Vals AI) | 45.0% | 38.1% | Claude Sonnet 5 |
| Terminal-Bench 2.1 (Vals AI) | 74.5% | Not measured | Only Claude Sonnet 5 measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 40.8% | Only Step 5 Preview measured |
| Vibe Code Bench 1-100 (Vals AI) | 13.8% | Not measured | Only Claude Sonnet 5 measured |
| SkillsBench (Vals AI) | 46.5% | Not measured | Only Claude Sonnet 5 measured |
| CyberBench (Vals AI) | 70.3% | Not measured | Only Claude Sonnet 5 measured |
| SciCode | 54.3% | 58.9% | Step 5 Preview |
| FrontierCode | 42.7% | Not measured | Only Claude Sonnet 5 measured |
| GSO-Bench | 37.3% | Not measured | Only Claude Sonnet 5 measured |
| WeirdML | 68.8% | Not measured | Only Claude Sonnet 5 measured |
| ALE-Bench | 1463.1 | Not measured | Only Claude Sonnet 5 measured |
| LMArena Text: coding | 1483 | 1485 | Step 5 Preview |
| LMArena Text: software and IT | 1474 | 1473 | Claude Sonnet 5 |
| LMArena WebDev: React | 1541 | 1583 | Step 5 Preview |
| LMArena WebDev: HTML | 1527 | 1556 | Step 5 Preview |
| LMArena WebDev: from an image | 1540 | 1550 | Step 5 Preview |
| SciCode | 10.7% | Not measured | Only Claude Sonnet 5 measured |
| Neither model has a result on the other 13 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Claude Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | 38.2 | 43.7 | Step 5 Preview |
| Epoch Capabilities Index | 156.9 | Not measured | Only Claude Sonnet 5 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index80
| Benchmark | Claude Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| AA Agentic Index | 43.6 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: agents building web apps | 1245 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: agents building full-stack apps | 1249 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: agents building mobile apps | 1215 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: agents building Android apps | 1225 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: agents building Godot games | 1225 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: agents building games | 1227 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: HTML slides | 1218 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: PowerPoint slides | 1216 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: spreadsheets | 1021 | Not measured | Only Claude Sonnet 5 measured |
| LiveBench research | 82.8% | 72.8% | Claude Sonnet 5 |
| LiveBench browser | 72.0% | 24.0% | Claude Sonnet 5 |
| LiveBench long agentic | 39.0% | 27.5% | Claude Sonnet 5 |
| SREBench (Vals AI) | 0.4% | 0.4% | Tie |
| Finance Agent (Vals AI) | 53.9% | 50.7% | Claude Sonnet 5 |
| Tax Agent Bench (Vals AI) | 29.4% | 27.3% | Claude Sonnet 5 |
| Legal Research Bench (Vals AI) | 41.8% | 40.4% | Claude Sonnet 5 |
| Excel Modeling Benchmark (Vals AI) | 66.3% | 57.1% | Claude Sonnet 5 |
| BioMysteryBench (Vals AI) | Not measured | 67.4% | Only Step 5 Preview measured |
| Terminal-Bench-Science (Vals AI) | 5.7% | 2.9% | Claude Sonnet 5 |
| Vals Science Index | Not measured | 29.6% | Only Step 5 Preview measured |
| APEX-Agents | 54.5% | Not measured | Only Claude Sonnet 5 measured |
| Vending-Bench 2 | $6,378 | Not measured | Only Claude Sonnet 5 measured |
| Neither model has a result on the other 18 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index43
| Benchmark | Claude Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| GPQA Diamond | 88.9% | Not measured | Only Claude Sonnet 5 measured |
| LiveBench reasoning | 88.7% | 83.8% | Claude Sonnet 5 |
| MysteryMechanism (Vals AI) | Not measured | 18.5% | Only Step 5 Preview measured |
| MMMU Pro (Vals AI) | 83.0% | Not measured | Only Claude Sonnet 5 measured |
| GPQA Diamond (Artificial Analysis run) | 91.1% | Not measured | Only Claude Sonnet 5 measured |
| Humanity's Last Exam (Artificial Analysis run) | 41.3% | 46.5% | Step 5 Preview |
| GPQA Diamond (Epoch AI run) | 90.5% | Not measured | Only Claude Sonnet 5 measured |
| SimpleBench | 60.6% | Not measured | Only Claude Sonnet 5 measured |
| Chess puzzles | 45.0% | Not measured | Only Claude Sonnet 5 measured |
| Mystery game puzzles | 35.0% | Not measured | Only Claude Sonnet 5 measured |
| LMArena Text: hard prompts | 1461 | 1461 | Step 5 Preview |
| LMArena Text: expert | 1489 | 1485 | Claude Sonnet 5 |
| LMArena Text: hard prompts in English | 1464 | 1454 | Claude Sonnet 5 |
| LMArena Vision: diagrams | 1293 | 1308 | Step 5 Preview |
| LMArena Vision: homework | 1311 | 1265 | Claude Sonnet 5 |
| Neither model has a result on the other 7 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| OTIS Mock AIME | 94.7% | Not measured | Only Claude Sonnet 5 measured |
| FrontierMath, tiers 1 to 3 | 65.6% | Not measured | Only Claude Sonnet 5 measured |
| FrontierMath, tier 4 | 29.3% | Not measured | Only Claude Sonnet 5 measured |
| ProofBench | 77.0% | 42.0% | Claude Sonnet 5 |
| LMArena Text: math | 1467 | 1458 | Claude Sonnet 5 |
| LMArena Text: mathematical work | 1481 | 1460 | Claude Sonnet 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 Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| MMLU Pro | 87.5% | Not measured | Only Claude Sonnet 5 measured |
| LegalBench (Vals AI) | 83.9% | Not measured | Only Claude Sonnet 5 measured |
| CorpFin (Vals AI) | 67.0% | Not measured | Only Claude Sonnet 5 measured |
| TaxEval (Vals AI) | 75.6% | Not measured | Only Claude Sonnet 5 measured |
| MortgageTax (Vals AI) | 70.0% | Not measured | Only Claude Sonnet 5 measured |
| MedCode (Vals AI) | 47.5% | Not measured | Only Claude Sonnet 5 measured |
| SimpleQA Verified | 33.7% | Not measured | Only Claude Sonnet 5 measured |
| LMArena Text: science | 1460 | 1454 | Claude Sonnet 5 |
| LMArena Text: medicine and healthcare | 1442 | 1439 | Claude Sonnet 5 |
| LMArena Text: legal and government | 1454 | 1437 | Claude Sonnet 5 |
| LMArena Text: business and finance | 1436 | 1435 | Claude Sonnet 5 |
| Neither model has a result on the other 7 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| Design Arena: websites | 1274 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: UI components | 1280 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: game dev | 1278 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: data viz | 1251 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: 3D | 1261 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: all code categories | 1276 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: SVG | 1193 | Not measured | Only Claude Sonnet 5 measured |
| Design Arena: ASCII art | 1207 | Not measured | Only Claude Sonnet 5 measured |
| LiveBench design | 82.0% | 76.9% | Claude Sonnet 5 |
GeneralLike-for-likePublic boards, shown as published, kept out of the index155
| Benchmark | Claude Sonnet 5 | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench data analysis | 71.7% | 63.5% | Claude Sonnet 5 |
| Public Benefits Bench (Vals AI) | 66.0% | 58.1% | Claude Sonnet 5 |
| SAGE (Vals AI) | 48.9% | Not measured | Only Claude Sonnet 5 measured |
| MedScribe (Vals AI) | 76.0% | Not measured | Only Claude Sonnet 5 measured |
| Vals Multimodal Index | 68.8% | Not measured | Only Claude Sonnet 5 measured |
| Long context reasoning (AA-LCR) | 82.0% | 88.3% | Step 5 Preview |
| DTBench | 92.5% | Not measured | Only Claude Sonnet 5 measured |
| LMCA | 50.0% | Not measured | Only Claude Sonnet 5 measured |
| Surface Evolver Bench | 60.0% | Not measured | Only Claude Sonnet 5 measured |
| LMArena Text | 1442 | 1440 | Claude Sonnet 5 |
| LMArena Text: instruction following | 1452 | 1438 | Claude Sonnet 5 |
| LMArena Text: creative writing | 1416 | 1409 | Claude Sonnet 5 |
| LMArena Vision | 1273 | 1265 | Claude Sonnet 5 |
| LMArena Text: English | 1450 | 1447 | Claude Sonnet 5 |
| LMArena Text: non-English | 1431 | 1428 | Claude Sonnet 5 |
| LMArena Text: Chinese | 1478 | 1500 | Step 5 Preview |
| LMArena Text: German | 1442 | Not measured | Only Claude Sonnet 5 measured |
| LMArena Text: Japanese | 1422 | 1383 | Claude Sonnet 5 |
| LMArena Text: Korean | 1412 | Not measured | Only Claude Sonnet 5 measured |
| LMArena Text: French | 1463 | 1438 | Claude Sonnet 5 |
| LMArena Text: Spanish | 1438 | 1441 | Step 5 Preview |
| LMArena Text: Russian | 1450 | 1433 | Claude Sonnet 5 |
| LMArena Text: Polish | 1425 | Not measured | Only Claude Sonnet 5 measured |
| LMArena Text: multi-turn | 1453 | 1437 | Claude Sonnet 5 |
| LMArena Text: longer queries | 1462 | 1449 | Claude Sonnet 5 |
| LMArena Text: writing and language | 1436 | 1425 | Claude Sonnet 5 |
| LMArena Text: entertainment and media | 1411 | 1412 | Step 5 Preview |
| LMArena Vision: English | 1275 | 1290 | Step 5 Preview |
| LMArena Vision: Chinese | 1331 | Not measured | Only Claude Sonnet 5 measured |
| LMArena Vision: reading text | 1288 | 1282 | Claude Sonnet 5 |
| LMArena Vision: humor | 1261 | Not measured | Only Claude Sonnet 5 measured |
| LMArena Vision: creative writing | 1246 | Not measured | Only Claude Sonnet 5 measured |
| LMArena Document | 1466 | Not measured | Only Claude Sonnet 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 | 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 Sonnet 5 | StepFun Step 5 Preview |
|---|---|---|
| Maker | Anthropic | StepFun |
| Weights | No public weights listed | Open weights |
| Released | June 30, 2026 | October 8, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $2.00 | $1.00 |
| Output $/Mtok | $10.00 | $2.70 |
| Coding index | 57.7 | 61.1 |
| Independent measurements behind it | 6 | 4 |
| Cost per solved task | $1.87 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Sonnet 5 better than Step 5 Preview for coding?
Pick Step 5 Preview for coding: it scores 61.1 on the Vibe Coding Index against 57.7 for Claude Sonnet 5, though on 4 benchmarks against 6. Pick Claude Sonnet 5 for work measured by Vibe Code Bench (Vals AI) or Code migration (Vals AI), where it leads.
Which is cheaper, Claude Sonnet 5 or Step 5 Preview?
Claude Sonnet 5 costs $2.00 per million input tokens and $10.00 per million output tokens; Step 5 Preview costs $1.00 and $2.70. Cost per solved task is known for Claude Sonnet 5 only.
Which has the bigger context window, Claude Sonnet 5 or Step 5 Preview?
Step 5 Preview, with 1.05M tokens against 1M.
How many benchmarks is the Claude Sonnet 5 vs Step 5 Preview comparison based on?
57 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 5's coding index rests on 6 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.