Step 3.5 Flash vs Hy4
Step 3.5 Flash costs 4.2x less per output token than Hy4 ($0.30 vs $1.2505 per million). Updated November 14, 2026; no benchmark has tested both models yet.
- Coding
- No data
- Overall
- No data
- Output $/M
- $0.30
- Coding
- 65.2
- Overall
- No data
- Output $/M
- $1.2505
Step 3.5 Flash or Hy4: which to pick
Only Hy4 has a coding score, 65.2 on the Vibe Coding Index; Step 3.5 Flash has none, so the two cannot be ranked on coding.
Pick Step 3.5 Flash for output tokens 4.2x cheaper ($0.30 vs $1.2505 per million).
No benchmark has tested both yet. Step 3.5 Flash has results on Terminal-Bench Hard (Artificial Analysis run), LMArena Text: coding and LMArena Text: software and IT; Hy4 on Terminal-Bench 4 (Vals AI), Vibe Code Bench (Vals AI) and Terminal-Bench 4.0 (Artificial Analysis run). Compare them on price and context instead.
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 Hy4 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
No call
Only Hy4 has a AA Intelligence Index result, 34.6.
Directional only
Web design
Design Arena: websites
No call
Only Hy4 has a Design Arena: websites result, 1251.
Directional only
General
Vals Index
No call
Only Hy4 has a Vals Index result, 59.4%.
Directional only
Long documents
Listed context window
Hy4
Hy4 takes 1.05M tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Step 3.5 Flash
Step 3.5 Flash $0.0003, Hy4 $0.0010 per turn.
List prices
At a glance
- Coding index
- Step 3.5 Flash not benchmarked, Hy4 65.2 from 2 benchmarks.
- Widest category
- None yet: no category has been tested on both models.
- Widest single gap
- None yet: no benchmark has tested both models.
- Output price
- Step 3.5 Flash $0.30 against Hy4 $1.2505 per million output tokens, 4.2x apart.
- Context window
- Step 3.5 Flash takes 262K tokens, Hy4 1.05M.
Benchmark by benchmark
Every board either model has a result on, a category to a fold; bars are each result on a 0 to 100 scale. Only one model is measured on each, so no row names a leader.
CodingDirectional onlySix of these boards feed the Vibe Coding Index9 boards measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| Terminal-Bench 4 (Vals AI) | Not measured | 39.4% | Only Hy4 measured |
| Vibe Code Bench (Vals AI) | Not measured | 81.0% | Only Hy4 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 32.6% | Not measured | Only Step 3.5 Flash measured |
| Terminal-Bench 4.0 (Artificial Analysis run) | Not measured | 37.4% | Only Hy4 measured |
| FrontierCode 2.0 | Not measured | 31.4% | Only Hy4 measured |
| LMArena Text: coding | 1435 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: software and IT | 1434 | Not measured | Only Step 3.5 Flash measured |
| GameBench 2 | Not measured | 48.7 | Only Hy4 measured |
| Terminal-Bench 4.0 | Not measured | 39.1% | Only Hy4 measured |
| Neither model has a result on the other 43 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index1 board measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| AA Intelligence Index | Not measured | 34.6 | Only Hy4 measured |
| Neither model has a result on the other 1 board here | |||
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index4 boards measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| Tax Agent Bench (Vals AI) | Not measured | 34.4% | Only Hy4 measured |
| Legal Research Bench (Vals AI) | Not measured | 41.4% | Only Hy4 measured |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 12.5% | Only Hy4 measured |
| τ²-Bench Telecom | 94.4% | Not measured | Only Step 3.5 Flash measured |
| Neither model has a result on the other 40 boards here | |||
ReasoningDirectional onlyPublic boards, shown as published, kept out of the index7 boards measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| GPQA Diamond (Artificial Analysis run) | 83.1% | Not measured | Only Step 3.5 Flash measured |
| Humanity's Last Exam (Artificial Analysis run) | 24.5% | Not measured | Only Step 3.5 Flash measured |
| HLE-Diamond (Artificial Analysis run) | Not measured | 32.7% | Only Hy4 measured |
| CritPt v2, hard subset (Artificial Analysis run) | Not measured | 39.0% | Only Hy4 measured |
| LMArena Text: hard prompts | 1410 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: expert | 1421 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: hard prompts in English | 1420 | Not measured | Only Step 3.5 Flash measured |
| Neither model has a result on the other 19 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index3 boards measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| LMArena Text: math | 1406 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: mathematical work | 1419 | Not measured | Only Step 3.5 Flash measured |
| MathArena | 18.7% | Not measured | Only Step 3.5 Flash measured |
| Neither model has a result on the other 11 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index5 boards measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| AA-Omniscience | Not measured | 5.4 | Only Hy4 measured |
| LMArena Text: science | 1414 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: medicine and healthcare | 1408 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: legal and government | 1407 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: business and finance | 1394 | Not measured | Only Step 3.5 Flash measured |
| Neither model has a result on the other 16 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index5 boards measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| Design Arena: websites | Not measured | 1251 | Only Hy4 measured |
| Design Arena: UI components | Not measured | 1197 | Only Hy4 measured |
| Design Arena: game dev | Not measured | 1271 | Only Hy4 measured |
| Design Arena: 3D | Not measured | 1251 | Only Hy4 measured |
| Design Arena: all code categories | Not measured | 1254 | Only Hy4 measured |
| Neither model has a result on the other 4 boards here | |||
GeneralDirectional onlyPublic boards, shown as published, kept out of the index20 boards measured
| Benchmark | Step 3.5 Flash | Hy4 | Leader |
|---|---|---|---|
| Vals Index | Not measured | 59.4% | Only Hy4 measured |
| IFBench | 66.5% | Not measured | Only Step 3.5 Flash measured |
| Long context reasoning (AA-LCR) | 63.0% | Not measured | Only Step 3.5 Flash measured |
| LMArena Text | 1402 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: instruction following | 1385 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: creative writing | 1357 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: English | 1417 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: non-English | 1385 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: Chinese | 1446 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: German | 1403 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: Japanese | 1353 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: Korean | 1350 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: French | 1421 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: Spanish | 1418 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: Russian | 1385 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: Polish | 1388 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: multi-turn | 1404 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: longer queries | 1402 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: writing and language | 1371 | Not measured | Only Step 3.5 Flash measured |
| LMArena Text: entertainment and media | 1359 | Not measured | Only Step 3.5 Flash measured |
| Neither model has a result on the other 29 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 3.5 Flash costs less
Repository review
50K input + 3K output tokens
Step 3.5 Flash costs less
Agent loop
200K input + 10K output tokens
Step 3.5 Flash 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 3.5 Flash | Tencent Hy4 |
|---|---|---|
| Maker | StepFun | Tencent |
| Weights | Open weights | Open weights |
| Released | January 29, 2026 | November 4, 2026 |
| Context window | 262K | 1.05M |
| Input $/Mtok | $0.10 | $0.417 |
| Output $/Mtok | $0.30 | $1.2505 |
| Coding index | Not benchmarked | 65.2 |
| Independent measurements behind it | 0 | 2 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Step 3.5 Flash better than Hy4 for coding?
Only Hy4 has a coding score, 65.2 on the Vibe Coding Index; Step 3.5 Flash has none, so the two cannot be ranked on coding. Pick Step 3.5 Flash for output tokens 4.2x cheaper ($0.30 vs $1.2505 per million).
Which is cheaper, Step 3.5 Flash or Hy4?
Step 3.5 Flash costs $0.10 per million input tokens and $0.30 per million output tokens; Hy4 costs $0.417 and $1.2505. Cost per solved task is known for neither of them.
Which has the bigger context window, Step 3.5 Flash or Hy4?
Hy4, with 1.05M tokens against 262K.
Has any benchmark tested both Step 3.5 Flash and Hy4?
No benchmark has tested both yet. Step 3.5 Flash has results on Terminal-Bench Hard (Artificial Analysis run), LMArena Text: coding and LMArena Text: software and IT; Hy4 on Terminal-Bench 4 (Vals AI), Vibe Code Bench (Vals AI) and Terminal-Bench 4.0 (Artificial Analysis run). Compare them on price and context instead. Data as of November 14, 2026.