Model comparison
Hy4 preview vs Step 3.5 Flash
Hy4 preview is the stronger model overall, scoring 45.3 to 42.3 on the Noometry Index. Step 3.5 Flash costs 8.3× less per token, which makes it the better buy when Hy4 preview's lead doesn't matter for your workload.
Last verified . 1 shared benchmarks.
Tencent
StepFunSummary
- They share 1 benchmark with published results for both. Hy4 preview scores higher in 3 categories and Step 3.5 Flash in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where Hy4 preview leads 55.7 to 42.6.
- The biggest single-benchmark swing is NYT Connections (extended): 68.2% for Hy4 preview and 28.4% for Step 3.5 Flash.
- Step 3.5 Flash is cheaper at $0.10 / $0.30 per million input/output tokens, against $0.83 / $2.50 for Hy4 preview.
- Hy4 preview accepts more context: 1.05M tokens versus 256K.
Side by side
| Hy4 preview | Step 3.5 Flash | |
|---|---|---|
| Provider | Tencent | StepFun |
| Noometry Index | 45.3 | 42.3 |
| Released | 2026-08-28 | 2026-01-29 |
| Weights | Open | Open |
| Context window | 1.05M | 256K |
| Max output | 64K | 256K |
| Input $ / M tokens | $0.83 | $0.10 |
| Output $ / M tokens | $2.50 | $0.30 |
| Results tracked | 3 | 19 |
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Category by category
Coding Hy4 preview leads
Hy4 preview: 51.6 (#38), Step 3.5 Flash: 42.4 (#105)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| LMArena WebDev | 1632 | — |
| LMArena Coding | — | 1436 |
Reasoning Hy4 preview leads
Hy4 preview: 31.9 (#79), Step 3.5 Flash: 22.2 (#202)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| NYT Connections (extended) | 68.2% | 28.4% |
| LMArena Hard Prompts | — | 1411 |
Math Hy4 preview leads
Hy4 preview: 55.7 (#42), Step 3.5 Flash: 42.6 (#84)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| MathArena Final-Answer Competitions | — | 66.8% |
| ProofBench | 75% | — |
| LMArena Math | — | 1408 |
Knowledge Not comparable
Hy4 preview: —, Step 3.5 Flash: 39.6 (#132)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | — | 1421 |
Multilingual Not comparable
Hy4 preview: —, Step 3.5 Flash: 50.5 (#119)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | — | 1385 |
| LMArena Chinese | — | 1447 |
| LMArena French | — | 1421 |
| LMArena German | — | 1405 |
| LMArena Japanese | — | 1354 |
| LMArena Korean | — | 1352 |
| LMArena Russian | — | 1385 |
| LMArena Spanish | — | 1419 |
Instruction Following Not comparable
Hy4 preview: —, Step 3.5 Flash: 73.1 (#124)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | — | 1385 |
Long Context Not comparable
Hy4 preview: —, Step 3.5 Flash: 42.8 (#117)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | — | 1402 |
Writing & Preference Not comparable
Hy4 preview: —, Step 3.5 Flash: 58.8 (#113)
| Benchmark | Hy4 preview | Step 3.5 Flash |
|---|---|---|
| LMArena Text | — | 1403 |
| LMArena Creative Writing | — | 1357 |
| LMArena Multi-Turn | — | 1405 |
Frequently asked questions
Is Hy4 preview better than Step 3.5 Flash?
Hy4 preview is the stronger model overall, scoring 45.3 to 42.3 on the Noometry Index. Step 3.5 Flash costs 8.3× less per token, which makes it the better buy when Hy4 preview's lead doesn't matter for your workload.
Which is cheaper, Hy4 preview or Step 3.5 Flash?
Step 3.5 Flash is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; Hy4 preview lists at $0.83 and $2.50.
Is Hy4 preview or Step 3.5 Flash better for coding?
Hy4 preview scores higher on coding benchmarks: 51.6 versus 42.4 in the Noometry coding category.
Which has the bigger context window?
Hy4 preview does, with 1.05M tokens against 256K.
How many benchmarks do Hy4 preview and Step 3.5 Flash share?
1 benchmark has published results for both models. Hy4 preview has 3 scored results on Noometry and Step 3.5 Flash has 19.