# Claude Opus 4.5 vs Step 3.7 Flash

> Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 36.5 on the Noometry Index. Step 3.7 Flash costs 24× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-opus-4-5-vs-step-3-7-flash
- Last updated: 2026-10-10
- Shared benchmarks: 2

## Summary

- They share 2 benchmarks with published results for both. Claude Opus 4.5 scores higher in 2 categories and Step 3.7 Flash in 1 category; 3 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Opus 4.5 leads 42.5 to 20.9.
- The biggest single-benchmark swing is NYT Connections (extended): 52.5% for Claude Opus 4.5 and 39.7% for Step 3.7 Flash.
- Step 3.7 Flash is cheaper at $0.18 / $1.11 per million input/output tokens, against $5 / $25 for Claude Opus 4.5.
- Step 3.7 Flash accepts more context: 256K tokens versus 200K.
- Step 3.7 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| Provider | Anthropic | StepFun |
| Noometry Index | 50.5 | 36.5 |
| Rank | 39 | 207 |
| Context | 200K | 256K |
| Input $/M | $5 | $0.18 |
| Output $/M | $25 | $1.11 |
| Weights | Proprietary | Open |

## Coding

- Claude Opus 4.5: 55.4 (#21)
- Step 3.7 Flash: 39.4 (#147)

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| ALE-Bench | 1,025 | 694.12 |
| SWE-bench Verified | 76.7% | — |
| SWE-bench Verified (bash only) | 76.8% | — |
| LMArena WebDev | 1493 | — |
| SWE-bench Multilingual | 70.7% | — |
| SciCode | — | 40% |
| GSO | 26.5% | — |
| WeirdML | 63.7% | — |
| LMArena Coding | 1504 | — |
| AlgoTune | 1.77 | — |

## Agentic & Tool Use

- Claude Opus 4.5: 47.2 (#11)
- Step 3.7 Flash: —

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| Terminal-Bench | 63.1% | — |
| Berkeley Function Calling Leaderboard | 77.5% | — |
| GDPval | 45.5% | — |
| Remote Labor Index | 3.8% | — |
| τ²-bench Airline | 84% | — |
| τ²-bench Banking | 24.7% | — |
| τ²-bench Retail | 79.6% | — |
| τ²-bench Telecom | 92.3% | — |
| Cybench | 82% | — |
| DeepResearch Bench | 54.8% | — |
| OSWorld | 66.3% | — |
| BALROG | 43.5% | — |
| LMArena Search | 1180 | — |
| METR Time Horizons | 75% | — |
| Vending-Bench 2 | 4,967 | — |

## Reasoning

- Claude Opus 4.5: 42.5 (#43)
- Step 3.7 Flash: 20.9 (#211)

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| NYT Connections (extended) | 52.5% | 39.7% |
| ARC-AGI-2 | 37.6% | — |
| SimpleBench | 62% | — |
| Kagi LLM Benchmark | 80.2% | — |
| ARC-AGI-1 | 80% | — |
| CritPt | — | 2.3% |
| Chess Puzzles | 12% | — |
| EnigmaEval | 11.9% | — |
| EBR-Bench | 14.3% | — |
| LMArena Hard Prompts | 1476 | — |
| Mystery Game Puzzles | 22% | — |
| DTBench | 89.9% | — |
| LMCA | 44.5% | — |
| Epoch Capabilities Index | 150.1 | — |
| ForecastBench | 60.7 | — |

## Math

- Claude Opus 4.5: 38.5 (#85)
- Step 3.7 Flash: 40.9 (#74)

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| FrontierMath (Tiers 1-3) | 34.4% | — |
| FrontierMath Tier 4 | 4.9% | — |
| MathArena Final-Answer Competitions | — | 68.5% |
| OTIS Mock AIME 2024-2025 | 86.1% | — |
| ProofBench | 36% | — |
| LMArena Math | 1463 | — |
| FrontierMath (Feb 2025 set) | 20.7% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |

## Knowledge

- Claude Opus 4.5: 56.4 (#38)
- Step 3.7 Flash: —

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| GPQA Diamond | 86% | — |
| Humanity's Last Exam | 25.2% | — |
| SimpleQA Verified | 45.7% | — |
| Vectara Hallucination Rate | 10.9% | — |
| LMArena Expert | 1488 | — |

## Multimodal

- Claude Opus 4.5: 31.1 (#99)
- Step 3.7 Flash: —

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| GeoBench | 75% | — |
| VPCT | 40% | — |
| Furniture Assembly | 28.3% | — |
| LMArena Document | 1462 | — |

## Multilingual

- Claude Opus 4.5: 54.5 (#45)
- Step 3.7 Flash: —

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| LMArena Non-English | 1438 | — |
| LMArena Chinese | 1470 | — |
| LMArena French | 1471 | — |
| LMArena German | 1449 | — |
| LMArena Japanese | 1415 | — |
| LMArena Korean | 1424 | — |
| LMArena Russian | 1448 | — |
| LMArena Spanish | 1455 | — |

## Instruction Following

- Claude Opus 4.5: 77.7 (#20)
- Step 3.7 Flash: —

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| LMArena Instruction Following | 1478 | — |

## Long Context

- Claude Opus 4.5: 46.4 (#21)
- Step 3.7 Flash: —

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| CL-bench | 21.1% | — |
| LMArena Longer Query | 1480 | — |

## Writing & Preference

- Claude Opus 4.5: 68.2 (#28)
- Step 3.7 Flash: —

| Benchmark | Claude Opus 4.5 | Step 3.7 Flash |
|---|---|---|
| LMArena Text | 1451 | — |
| LMArena Creative Writing | 1445 | — |
| EQ-Bench Creative Writing | 1687 | — |
| LMArena Multi-Turn | 1466 | — |

## FAQ

### Is Claude Opus 4.5 better than Step 3.7 Flash?

Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 36.5 on the Noometry Index. Step 3.7 Flash costs 24× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

### Which is cheaper, Claude Opus 4.5 or Step 3.7 Flash?

Step 3.7 Flash is cheaper. It lists at $0.18 per million input tokens and $1.11 per million output tokens; Claude Opus 4.5 lists at $5 and $25.

### Is Claude Opus 4.5 or Step 3.7 Flash better for coding?

Claude Opus 4.5 scores higher on coding benchmarks: 55.4 versus 39.4 in the Noometry coding category.

### Which has the bigger context window?

Step 3.7 Flash does, with 256K tokens against 200K.

### How many benchmarks do Claude Opus 4.5 and Step 3.7 Flash share?

2 benchmarks have published results for both models. Claude Opus 4.5 has 69 scored results on Noometry and Step 3.7 Flash has 5.