Model comparison
Grok 4.5 vs Step 3.5 Flash
Grok 4.5 is the stronger model overall, scoring 55.0 to 42.3 on the Noometry Index. Step 3.5 Flash costs 20× less per token, which makes it the better buy when Grok 4.5's lead doesn't matter for your workload.
Last verified . 18 shared benchmarks.
StepFunSummary
- They share 18 benchmarks with published results for both. Grok 4.5 scores higher in 8 categories and Step 3.5 Flash in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.5 leads 56.1 to 22.2.
- The biggest single-benchmark swing is NYT Connections (extended): 79.9% for Grok 4.5 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 $2 / $6 for Grok 4.5.
- Grok 4.5 accepts more context: 500K tokens versus 256K.
- Step 3.5 Flash has downloadable open weights; the other is API-only.
Side by side
| Grok 4.5 | Step 3.5 Flash | |
|---|---|---|
| Provider | xAI | StepFun |
| Noometry Index | 55.0 | 42.3 |
| Released | 2026-07-08 | 2026-01-29 |
| Weights | Proprietary | Open |
| Context window | 500K | 256K |
| Max output | 500K | 256K |
| Input $ / M tokens | $2 | $0.10 |
| Output $ / M tokens | $6 | $0.30 |
| Results tracked | 52 | 19 |
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Category by category
Coding Grok 4.5 leads
Grok 4.5: 52.2 (#35), Step 3.5 Flash: 42.4 (#105)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1474 | 1436 |
| DeepSWE | 53.8% | — |
| FrontierCode | 42.4% | — |
| LMArena WebDev | 1553 | — |
| SciCode | 54.1% | — |
| WeirdML | 46.4% | — |
| ALE-Bench | 1,309 | — |
Agentic & Tool Use Not comparable
Grok 4.5: 44.4 (#17), Step 3.5 Flash: —
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| APEX-Agents | 56.2% | — |
| τ²-bench Banking | 47.9% | — |
| PostTrainBench | 23.4% | — |
| GBAEval | 65.4% | — |
| GDP.pdf | 14% | — |
| LMArena Search | 1213 | — |
| Vending-Bench 2 | 3,887 | — |
Reasoning Grok 4.5 leads
Grok 4.5: 56.1 (#25), Step 3.5 Flash: 22.2 (#202)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| NYT Connections (extended) | 79.9% | 28.4% |
| LMArena Hard Prompts | 1462 | 1411 |
| ARC-AGI-2 | 52.6% | — |
| SimpleBench | 70% | — |
| Kagi LLM Benchmark | 83.5% | — |
| ARC-AGI-1 | 87.2% | — |
| CritPt | 15.4% | — |
| Chess Puzzles | 36% | — |
| DTBench | 96.5% | — |
| LMCA | 45.2% | — |
| Surface Evolver Bench | 74.4% | — |
| Epoch Capabilities Index | 153.92 | — |
Math Grok 4.5 leads
Grok 4.5: 60.9 (#35), Step 3.5 Flash: 42.6 (#84)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Math | 1459 | 1408 |
| FrontierMath (Tiers 1-3) | 57.2% | — |
| FrontierMath Tier 4 | 24.4% | — |
| MathArena Final-Answer Competitions | — | 66.8% |
| OTIS Mock AIME 2024-2025 | 97.8% | — |
| ProofBench | 31% | — |
Knowledge Grok 4.5 leads
Grok 4.5: 62.3 (#24), Step 3.5 Flash: 39.6 (#132)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1466 | 1421 |
| GPQA Diamond | 93.4% | — |
| SimpleQA Verified | 48.3% | — |
Multimodal Not comparable
Grok 4.5: 37.6 (#72), Step 3.5 Flash: —
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Vision | 1288 | — |
| Blueprint-Bench 2 | 27.3% | — |
| Furniture Assembly | 22.5% | — |
| LMArena Document | 1452 | — |
Multilingual Grok 4.5 leads
Grok 4.5: 54.4 (#42), Step 3.5 Flash: 50.5 (#119)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1440 | 1385 |
| LMArena Chinese | 1496 | 1447 |
| LMArena French | 1456 | 1421 |
| LMArena German | 1446 | 1405 |
| LMArena Japanese | 1428 | 1354 |
| LMArena Korean | 1404 | 1352 |
| LMArena Russian | 1448 | 1385 |
| LMArena Spanish | 1450 | 1419 |
Instruction Following Grok 4.5 leads
Grok 4.5: 76.0 (#48), Step 3.5 Flash: 73.1 (#124)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1446 | 1385 |
Long Context Grok 4.5 leads
Grok 4.5: 44.8 (#56), Step 3.5 Flash: 42.8 (#117)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1463 | 1402 |
Writing & Preference Grok 4.5 leads
Grok 4.5: 65.8 (#42), Step 3.5 Flash: 58.8 (#113)
| Benchmark | Grok 4.5 | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1448 | 1403 |
| LMArena Creative Writing | 1442 | 1357 |
| LMArena Multi-Turn | 1456 | 1405 |
| EQ-Bench Creative Writing | 1579 | — |
Frequently asked questions
Is Grok 4.5 better than Step 3.5 Flash?
Grok 4.5 is the stronger model overall, scoring 55.0 to 42.3 on the Noometry Index. Step 3.5 Flash costs 20× less per token, which makes it the better buy when Grok 4.5's lead doesn't matter for your workload.
Which is cheaper, Grok 4.5 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 4.5 lists at $2 and $6.
Is Grok 4.5 or Step 3.5 Flash better for coding?
Grok 4.5 scores higher on coding benchmarks: 52.2 versus 42.4 in the Noometry coding category.
Which has the bigger context window?
Grok 4.5 does, with 500K tokens against 256K.
How many benchmarks do Grok 4.5 and Step 3.5 Flash share?
18 benchmarks have published results for both models. Grok 4.5 has 52 scored results on Noometry and Step 3.5 Flash has 19.