# Claude Sonnet 5.5 vs Step 3.7 Flash

> Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 36.5 on the Noometry Index. Step 3.7 Flash costs 9.6× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

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

## Summary

- They share 3 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 3 categories and Step 3.7 Flash in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 88.7 to 40.9.
- The biggest single-benchmark swing is CritPt: 31.4% for Claude Sonnet 5.5 and 2.3% for Step 3.7 Flash.
- Step 3.7 Flash is cheaper at $0.18 / $1.11 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 256K.
- Step 3.7 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Sonnet 5.5 | Step 3.7 Flash |
|---|---|---|
| Provider | Anthropic | StepFun |
| Noometry Index | 60.5 | 36.5 |
| Rank | 10 | 207 |
| Context | 1M | 256K |
| Input $/M | $2 | $0.18 |
| Output $/M | $10 | $1.11 |
| Weights | Proprietary | Open |

## Coding

- Claude Sonnet 5.5: 65.5 (#6)
- Step 3.7 Flash: 39.4 (#147)

| Benchmark | Claude Sonnet 5.5 | Step 3.7 Flash |
|---|---|---|
| SciCode | 61% | 40% |
| ALE-Bench | 1,819 | 694.12 |
| FrontierCode | 52.1% | — |
| CursorBench | 55.5% | — |
| LMArena WebDev | 1699 | — |
| FrontierSWE | 61.9% | — |

## Agentic & Tool Use

- Claude Sonnet 5.5: 44.9 (#14)
- Step 3.7 Flash: —

| Benchmark | Claude Sonnet 5.5 | Step 3.7 Flash |
|---|---|---|
| APEX-Agents | 75.5% | — |

## Reasoning

- Claude Sonnet 5.5: 52.4 (#29)
- Step 3.7 Flash: 20.9 (#211)

| Benchmark | Claude Sonnet 5.5 | Step 3.7 Flash |
|---|---|---|
| CritPt | 31.4% | 2.3% |
| NYT Connections (extended) | — | 39.7% |
| Mystery Game Puzzles | 65% | — |

## Math

- Claude Sonnet 5.5: 88.7 (#4)
- Step 3.7 Flash: 40.9 (#74)

| Benchmark | Claude Sonnet 5.5 | Step 3.7 Flash |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | — |
| FrontierMath Tier 4 | 80.5% | — |
| MathArena Final-Answer Competitions | — | 68.5% |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |

## Knowledge

- Claude Sonnet 5.5: 66.0 (#11)
- Step 3.7 Flash: —

| Benchmark | Claude Sonnet 5.5 | Step 3.7 Flash |
|---|---|---|
| GPQA Diamond | 95.6% | — |
| SimpleQA Verified | 46.5% | — |

## Multimodal

- Claude Sonnet 5.5: 53.2 (#5)
- Step 3.7 Flash: —

| Benchmark | Claude Sonnet 5.5 | Step 3.7 Flash |
|---|---|---|
| Furniture Assembly | 75% | — |

## FAQ

### Is Claude Sonnet 5.5 better than Step 3.7 Flash?

Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 36.5 on the Noometry Index. Step 3.7 Flash costs 9.6× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

### Which is cheaper, Claude Sonnet 5.5 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 Sonnet 5.5 lists at $2 and $10.

### Is Claude Sonnet 5.5 or Step 3.7 Flash better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 65.5 versus 39.4 in the Noometry coding category.

### Which has the bigger context window?

Claude Sonnet 5.5 does, with 1M tokens against 256K.

### How many benchmarks do Claude Sonnet 5.5 and Step 3.7 Flash share?

3 benchmarks have published results for both models. Claude Sonnet 5.5 has 16 scored results on Noometry and Step 3.7 Flash has 5.