Step 5 Preview vs Solar Pro 4
Step 5 Preview leads Solar Pro 4 on the Artificial Analysis Intelligence Index, 43.7 to 28.2, and Solar Pro 4 costs 4.5x less per output token ($0.60 vs $2.70 per million). Updated October 22, 2026; 32 benchmarks have a result for both.
Step 5 Preview or Solar Pro 4: which to pick
Only Step 5 Preview has a coding score, 61.1 on the Vibe Coding Index; Solar Pro 4 has none, so the two cannot be ranked on coding.
Pick Solar Pro 4 for output tokens 4.5x cheaper ($0.60 vs $2.70 per million).
- Shared results
- 32
- Step 5 Preview only
- 29
- Solar Pro 4 only
- 13
- Like-for-like categories
- 6 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 Step 5 Preview has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Step 5 Preview
Step 5 Preview leads, 43.7 against 28.2.
Same board, both measured
Web design
Design Arena: websites
No call
Only Solar Pro 4 has a Design Arena: websites result, 1176.
Directional only
Long documents
Listed context window
Step 5 Preview
Step 5 Preview takes 1.05M tokens against 524K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Solar Pro 4
Step 5 Preview $0.0024, Solar Pro 4 $0.0004 per turn.
List prices
At a glance
- Coding index
- Step 5 Preview 61.1 from 4 benchmarks, Solar Pro 4 not benchmarked.
- Widest category
- Coding, 20.2 points apart on average over 6 shared benchmarks.
- Widest single gap
- LMArena WebDev: React: Step 5 Preview 1583 against Solar Pro 4 1363, 36.6 points apart on a 0 to 100 scale.
- Output price
- Step 5 Preview $2.70 against Solar Pro 4 $0.60 per million output tokens, 4.5x apart.
- Context window
- Step 5 Preview takes 1.05M tokens, Solar Pro 4 524K.
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 | Step 5 Preview | Bars | Solar Pro 4 | Ties |
|---|---|---|---|---|
| Coding | 6 | 0 | ||
| Intelligence | 1 | 0 | ||
| Reasoning | 4 | 0 | ||
| Math | 2 | 0 | ||
| Knowledge | 4 | 0 | ||
| General | 15 | 0 | ||
| All shared boards | 32 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index60
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| LiveBench coding | 85.6% | Not measured | Only Step 5 Preview measured |
| LMArena WebDev | 1567 | 1371 | Step 5 Preview |
| AA Coding Index | Not measured | 52.7 | Only Solar Pro 4 measured |
| Terminal-Bench 4 (Vals AI) | 31.8% | Not measured | Only Step 5 Preview measured |
| Vibe Code Bench (Vals AI) | 70.4% | Not measured | Only Step 5 Preview measured |
| Code migration (Vals AI) | 39.0% | Not measured | Only Step 5 Preview measured |
| IOI (Vals AI) | 38.1% | Not measured | Only Step 5 Preview measured |
| SWE-bench Multimodal (Vals AI) | 40.8% | Not measured | Only Step 5 Preview measured |
| SciCode | 58.9% | 48.0% | Step 5 Preview |
| ALE-Bench | Not measured | 179.3 | Only Solar Pro 4 measured |
| LMArena Text: coding | 1485 | 1438 | Step 5 Preview |
| LMArena Text: software and IT | 1473 | 1431 | Step 5 Preview |
| LMArena WebDev: React | 1583 | 1363 | Step 5 Preview |
| LMArena WebDev: HTML | 1556 | 1371 | Step 5 Preview |
| LMArena WebDev: from an image | 1550 | Not measured | Only Step 5 Preview measured |
| Neither model has a result on the other 24 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| AA Intelligence Index | 43.7 | 28.2 | Step 5 Preview |
| Neither model has a result on the other 1 board here | |||
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | Not measured | 1105 | Only Solar Pro 4 measured |
| LiveBench research | 72.8% | Not measured | Only Step 5 Preview measured |
| LiveBench browser | 24.0% | Not measured | Only Step 5 Preview measured |
| LiveBench long agentic | 27.5% | Not measured | Only Step 5 Preview measured |
| SREBench (Vals AI) | 0.4% | Not measured | Only Step 5 Preview measured |
| Finance Agent (Vals AI) | 50.7% | Not measured | Only Step 5 Preview measured |
| Tax Agent Bench (Vals AI) | 27.3% | Not measured | Only Step 5 Preview measured |
| Legal Research Bench (Vals AI) | 40.4% | Not measured | Only Step 5 Preview measured |
| Excel Modeling Benchmark (Vals AI) | 57.1% | Not measured | Only Step 5 Preview measured |
| BioMysteryBench (Vals AI) | 67.4% | Not measured | Only Step 5 Preview measured |
| Terminal-Bench-Science (Vals AI) | 2.9% | Not measured | Only Step 5 Preview measured |
| Vals Science Index | 29.6% | Not measured | Only Step 5 Preview measured |
| Neither model has a result on the other 29 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| LiveBench reasoning | 83.8% | Not measured | Only Step 5 Preview measured |
| MysteryMechanism (Vals AI) | 18.5% | Not measured | Only Step 5 Preview measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 89.1% | Only Solar Pro 4 measured |
| Humanity's Last Exam (Artificial Analysis run) | 46.5% | 29.8% | Step 5 Preview |
| LMArena Text: hard prompts | 1461 | 1400 | Step 5 Preview |
| LMArena Text: expert | 1485 | 1428 | Step 5 Preview |
| LMArena Text: hard prompts in English | 1454 | 1427 | Step 5 Preview |
| LMArena Vision: diagrams | 1308 | Not measured | Only Step 5 Preview measured |
| LMArena Vision: homework | 1265 | Not measured | Only Step 5 Preview measured |
| Neither model has a result on the other 13 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| ProofBench | 42.0% | Not measured | Only Step 5 Preview measured |
| LMArena Text: math | 1458 | 1421 | Step 5 Preview |
| LMArena Text: mathematical work | 1460 | 1427 | Step 5 Preview |
| Neither model has a result on the other 10 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| LMArena Text: science | 1454 | 1404 | Step 5 Preview |
| LMArena Text: medicine and healthcare | 1439 | 1374 | Step 5 Preview |
| LMArena Text: legal and government | 1437 | 1383 | Step 5 Preview |
| LMArena Text: business and finance | 1435 | 1381 | Step 5 Preview |
| Neither model has a result on the other 14 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index7 boards, none shared
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| Design Arena: websites | Not measured | 1176 | Only Solar Pro 4 measured |
| Design Arena: UI components | Not measured | 1147 | Only Solar Pro 4 measured |
| Design Arena: game dev | Not measured | 1169 | Only Solar Pro 4 measured |
| Design Arena: data viz | Not measured | 1177 | Only Solar Pro 4 measured |
| Design Arena: 3D | Not measured | 1178 | Only Solar Pro 4 measured |
| Design Arena: all code categories | Not measured | 1182 | Only Solar Pro 4 measured |
| LiveBench design | 76.9% | Not measured | Only Step 5 Preview measured |
| Neither model has a result on the other 2 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index150
| Benchmark | Step 5 Preview | Solar Pro 4 | Leader |
|---|---|---|---|
| LiveBench data analysis | 63.5% | Not measured | Only Step 5 Preview measured |
| Public Benefits Bench (Vals AI) | 58.1% | Not measured | Only Step 5 Preview measured |
| Long context reasoning (AA-LCR) | 88.3% | 70.7% | Step 5 Preview |
| LMArena Text | 1440 | 1388 | Step 5 Preview |
| LMArena Text: instruction following | 1438 | 1375 | Step 5 Preview |
| LMArena Text: creative writing | 1409 | 1317 | Step 5 Preview |
| LMArena Vision | 1265 | Not measured | Only Step 5 Preview measured |
| LMArena Text: English | 1447 | 1414 | Step 5 Preview |
| LMArena Text: non-English | 1428 | 1363 | Step 5 Preview |
| LMArena Text: Chinese | 1500 | 1422 | Step 5 Preview |
| LMArena Text: German | Not measured | 1358 | Only Solar Pro 4 measured |
| LMArena Text: Japanese | 1383 | 1320 | Step 5 Preview |
| LMArena Text: Korean | Not measured | 1383 | Only Solar Pro 4 measured |
| LMArena Text: French | 1438 | 1400 | Step 5 Preview |
| LMArena Text: Spanish | 1441 | 1409 | Step 5 Preview |
| LMArena Text: Russian | 1433 | 1357 | Step 5 Preview |
| LMArena Text: Polish | Not measured | 1304 | Only Solar Pro 4 measured |
| LMArena Text: multi-turn | 1437 | 1385 | Step 5 Preview |
| LMArena Text: longer queries | 1449 | 1382 | Step 5 Preview |
| LMArena Text: writing and language | 1425 | 1344 | Step 5 Preview |
| LMArena Text: entertainment and media | 1412 | 1332 | Step 5 Preview |
| LMArena Vision: English | 1290 | Not measured | Only Step 5 Preview measured |
| LMArena Vision: reading text | 1282 | Not measured | Only Step 5 Preview measured |
| Neither model has a result on the other 23 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Step 5 Preview | Solar Pro 4 | 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
Solar Pro 4 costs less
Repository review
50K input + 3K output tokens
Solar Pro 4 costs less
Agent loop
200K input + 10K output tokens
Solar Pro 4 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 | StepFun Step 5 Preview | Upstage Solar Pro 4 |
|---|---|---|
| Maker | StepFun | Upstage |
| Weights | Open weights | No public weights listed |
| Released | October 8, 2026 | August 10, 2026 |
| Context window | 1.05M | 524K |
| Input $/Mtok | $1.00 | $0.15 |
| Output $/Mtok | $2.70 | $0.60 |
| Coding index | 61.1 | Not benchmarked |
| Independent measurements behind it | 4 | 1 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Step 5 Preview better than Solar Pro 4 for coding?
Only Step 5 Preview has a coding score, 61.1 on the Vibe Coding Index; Solar Pro 4 has none, so the two cannot be ranked on coding. Pick Solar Pro 4 for output tokens 4.5x cheaper ($0.60 vs $2.70 per million).
Which is cheaper, Step 5 Preview or Solar Pro 4?
Step 5 Preview costs $1.00 per million input tokens and $2.70 per million output tokens; Solar Pro 4 costs $0.15 and $0.60. Cost per solved task is known for neither of them.
Which has the bigger context window, Step 5 Preview or Solar Pro 4?
Step 5 Preview, with 1.05M tokens against 524K.
How many benchmarks is the Step 5 Preview vs Solar Pro 4 comparison based on?
32 benchmarks have a result for both models as of October 22, 2026. Step 5 Preview's coding index rests on 4 independent benchmarks and Solar Pro 4's on 1. Where only one model has a result, the page says so instead of naming a winner.