Model comparison
Solar Pro4 vs Step 5 Preview
Step 5 Preview is the stronger model overall, scoring 47.9 to 42.1 on the Noometry Index. Solar Pro4 costs 2.7× less per token, which makes it the better buy when Step 5 Preview's lead doesn't matter for your workload.
Last verified . 14 shared benchmarks.
Upstage
StepFunSummary
- They share 14 benchmarks with published results for both. Solar Pro4 scores higher in 0 categories and Step 5 Preview in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in coding, where Step 5 Preview leads 51.8 to 40.1.
- Solar Pro4 is cheaper at $0.30 / $1.20 per million input/output tokens, against $1 / $2.70 for Step 5 Preview.
- Step 5 Preview accepts more context: 1.02M tokens versus 524K.
Side by side
| Solar Pro4 | Step 5 Preview | |
|---|---|---|
| Provider | Upstage | StepFun |
| Noometry Index | 42.1 | 47.9 |
| Released | 2026-08-06 | 2026-09-16 |
| Weights | Proprietary | Proprietary |
| Context window | 524K | 1.02M |
| Max output | 131K | 66K |
| Input $ / M tokens | $0.30 | $1 |
| Output $ / M tokens | $1.20 | $2.70 |
| Results tracked | 18 | 18 |
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Category by category
Coding Step 5 Preview leads
Solar Pro4: 40.1 (#149), Step 5 Preview: 51.8 (#36)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena WebDev | 1371 | 1564 |
| LMArena Coding | 1437 | 1480 |
| SciCode | — | 58.9% |
Reasoning Step 5 Preview leads
Solar Pro4: 28.5 (#104), Step 5 Preview: 40.0 (#57)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1465 |
| CritPt | — | 20.9% |
Math Step 5 Preview leads
Solar Pro4: 38.8 (#128), Step 5 Preview: 46.1 (#72)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Math | 1416 | 1470 |
| ProofBench | — | 42% |
Knowledge Step 5 Preview leads
Solar Pro4: 39.8 (#129), Step 5 Preview: 41.2 (#112)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Expert | 1427 | 1470 |
Multimodal Not comparable
Solar Pro4: —, Step 5 Preview: 41.0 (#41)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Vision | — | 1267 |
Multilingual Step 5 Preview leads
Solar Pro4: 48.7 (#139), Step 5 Preview: 53.8 (#54)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Non-English | 1361 | 1432 |
| LMArena Chinese | 1415 | 1519 |
| LMArena Russian | 1360 | 1436 |
| LMArena Spanish | 1401 | 1439 |
| LMArena French | 1397 | — |
| LMArena German | 1364 | — |
| LMArena Japanese | 1309 | — |
| LMArena Korean | 1382 | — |
Instruction Following Step 5 Preview leads
Solar Pro4: 72.7 (#132), Step 5 Preview: 76.0 (#50)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Instruction Following | 1377 | 1444 |
Long Context Step 5 Preview leads
Solar Pro4: 42.1 (#130), Step 5 Preview: 44.5 (#64)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Longer Query | 1381 | 1455 |
Writing & Preference Step 5 Preview leads
Solar Pro4: 56.5 (#138), Step 5 Preview: 62.8 (#71)
| Benchmark | Solar Pro4 | Step 5 Preview |
|---|---|---|
| LMArena Text | 1386 | 1442 |
| LMArena Creative Writing | 1316 | 1410 |
| LMArena Multi-Turn | 1385 | 1447 |
Frequently asked questions
Is Solar Pro4 better than Step 5 Preview?
Step 5 Preview is the stronger model overall, scoring 47.9 to 42.1 on the Noometry Index. Solar Pro4 costs 2.7× less per token, which makes it the better buy when Step 5 Preview's lead doesn't matter for your workload.
Which is cheaper, Solar Pro4 or Step 5 Preview?
Solar Pro4 is cheaper. It lists at $0.30 per million input tokens and $1.20 per million output tokens; Step 5 Preview lists at $1 and $2.70.
Is Solar Pro4 or Step 5 Preview better for coding?
Step 5 Preview scores higher on coding benchmarks: 51.8 versus 40.1 in the Noometry coding category.
Which has the bigger context window?
Step 5 Preview does, with 1.02M tokens against 524K.
How many benchmarks do Solar Pro4 and Step 5 Preview share?
14 benchmarks have published results for both models. Solar Pro4 has 18 scored results on Noometry and Step 5 Preview has 18.