Model comparison
Grok 4.20 (Non-Reasoning) vs Step 3.5 Flash
Grok 4.20 (Non-Reasoning) is the stronger model overall, scoring 48.6 to 42.3 on the Noometry Index. Step 3.5 Flash costs 10× less per token, which makes it the better buy when Grok 4.20 (Non-Reasoning)'s lead doesn't matter for your workload.
Last verified . 18 shared benchmarks.
StepFunSummary
- They share 18 benchmarks with published results for both. Grok 4.20 (Non-Reasoning) scores higher in 7 categories and Step 3.5 Flash in 1 category; 7 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.20 (Non-Reasoning) leads 52.3 to 22.2.
- The biggest single-benchmark swing is NYT Connections (extended): 85.4% for Grok 4.20 (Non-Reasoning) 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 $1.25 / $2.50 for Grok 4.20 (Non-Reasoning).
- Grok 4.20 (Non-Reasoning) accepts more context: 1M tokens versus 256K.
- Step 3.5 Flash has downloadable open weights; the other is API-only.
Side by side
| Grok 4.20 (Non-Reasoning) | Step 3.5 Flash | |
|---|---|---|
| Provider | xAI | StepFun |
| Noometry Index | 48.6 | 42.3 |
| Released | 2026-02-17 | 2026-01-29 |
| Weights | Proprietary | Open |
| Context window | 1M | 256K |
| Max output | 30K | 256K |
| Input $ / M tokens | $1.25 | $0.10 |
| Output $ / M tokens | $2.50 | $0.30 |
| Results tracked | 46 | 19 |
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Category by category
Coding Too close to call
Grok 4.20 (Non-Reasoning): 42.1 (#112), Step 3.5 Flash: 42.4 (#105)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1459 | 1436 |
| LMArena WebDev | 1375 | — |
| WeirdML | 52.3% | — |
| ALE-Bench | 1,150 | — |
Agentic & Tool Use Not comparable
Grok 4.20 (Non-Reasoning): 34.4 (#46), Step 3.5 Flash: —
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| Terminal-Bench | 57.3% | — |
| τ²-bench Banking | 18% | — |
| LMArena Search | 1189 | — |
| Vending-Bench 2 | 4,663 | — |
Reasoning Grok 4.20 (Non-Reasoning) leads
Grok 4.20 (Non-Reasoning): 52.3 (#32), Step 3.5 Flash: 22.2 (#202)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| NYT Connections (extended) | 85.4% | 28.4% |
| LMArena Hard Prompts | 1451 | 1411 |
| ARC-AGI-2 | 65.1% | — |
| Kagi LLM Benchmark | 75% | — |
| ARC-AGI-1 | 89.5% | — |
| Chess Puzzles | 24% | — |
| Thematic Generalization | 63.8% | — |
| DTBench | 90.1% | — |
| LMCA | 38.7% | — |
| Epoch Capabilities Index | 151.98 | — |
| ForecastBench | 61.4 | — |
Math Grok 4.20 (Non-Reasoning) leads
Grok 4.20 (Non-Reasoning): 48.2 (#65), Step 3.5 Flash: 42.6 (#84)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Math | 1455 | 1408 |
| FrontierMath (Tiers 1-3) | 44.9% | — |
| FrontierMath Tier 4 | 17.1% | — |
| MathArena Final-Answer Competitions | — | 66.8% |
| OTIS Mock AIME 2024-2025 | 92.2% | — |
| ProofBench | 14% | — |
Knowledge Grok 4.20 (Non-Reasoning) leads
Grok 4.20 (Non-Reasoning): 52.8 (#60), Step 3.5 Flash: 39.6 (#132)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1439 | 1421 |
| GPQA Diamond | 89.3% | — |
| SimpleQA Verified | 30.2% | — |
Multimodal Not comparable
Grok 4.20 (Non-Reasoning): 33.3 (#98), Step 3.5 Flash: —
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Vision | 1263 | — |
| Blueprint-Bench 2 | 0% | — |
| LMArena Document | 1416 | — |
Multilingual Grok 4.20 (Non-Reasoning) leads
Grok 4.20 (Non-Reasoning): 54.5 (#40), Step 3.5 Flash: 50.5 (#119)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1441 | 1385 |
| LMArena Chinese | 1481 | 1447 |
| LMArena French | 1476 | 1421 |
| LMArena German | 1465 | 1405 |
| LMArena Japanese | 1449 | 1354 |
| LMArena Korean | 1417 | 1352 |
| LMArena Russian | 1458 | 1385 |
| LMArena Spanish | 1443 | 1419 |
Instruction Following Grok 4.20 (Non-Reasoning) leads
Grok 4.20 (Non-Reasoning): 74.8 (#83), Step 3.5 Flash: 73.1 (#124)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1420 | 1385 |
Long Context Grok 4.20 (Non-Reasoning) leads
Grok 4.20 (Non-Reasoning): 45.5 (#34), Step 3.5 Flash: 42.8 (#117)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1437 | 1402 |
| CL-bench | 22.2% | — |
| CL-bench Life | 11.9% | — |
Writing & Preference Grok 4.20 (Non-Reasoning) leads
Grok 4.20 (Non-Reasoning): 65.7 (#44), Step 3.5 Flash: 58.8 (#113)
| Benchmark | Grok 4.20 (Non-Reasoning) | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1451 | 1403 |
| LMArena Creative Writing | 1438 | 1357 |
| LMArena Multi-Turn | 1456 | 1405 |
| EQ-Bench Creative Writing | 1574 | — |
Frequently asked questions
Is Grok 4.20 (Non-Reasoning) better than Step 3.5 Flash?
Grok 4.20 (Non-Reasoning) is the stronger model overall, scoring 48.6 to 42.3 on the Noometry Index. Step 3.5 Flash costs 10× less per token, which makes it the better buy when Grok 4.20 (Non-Reasoning)'s lead doesn't matter for your workload.
Which is cheaper, Grok 4.20 (Non-Reasoning) 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; Grok 4.20 (Non-Reasoning) lists at $1.25 and $2.50.
Is Grok 4.20 (Non-Reasoning) or Step 3.5 Flash better for coding?
They score almost the same on coding (42.1 vs 42.4); test both on your own repository before choosing.
Which has the bigger context window?
Grok 4.20 (Non-Reasoning) does, with 1M tokens against 256K.
How many benchmarks do Grok 4.20 (Non-Reasoning) and Step 3.5 Flash share?
18 benchmarks have published results for both models. Grok 4.20 (Non-Reasoning) has 46 scored results on Noometry and Step 3.5 Flash has 19.