# Claude Opus 5.5 vs Mistral Small 3

> Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 30.9 on the Noometry Index. Mistral Small 3 costs 139× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-opus-5-5-vs-mistral-small-3
- Last updated: 2026-10-10
- Shared benchmarks: 14

## Summary

- They share 14 benchmarks with published results for both. Claude Opus 5.5 scores higher in 8 categories and Mistral Small 3 in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 92.4 to 15.3.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 100% for Claude Opus 5.5 and 6.7% for Mistral Small 3.
- Mistral Small 3 is cheaper at $0.05 / $0.08 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
- Claude Opus 5.5 accepts more context: 1M tokens versus 33K.
- Mistral Small 3 has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| Provider | Anthropic | Mistral AI |
| Noometry Index | 68.5 | 30.9 |
| Rank | 3 | 268 |
| Context | 1M | 33K |
| Input $/M | $4 | $0.05 |
| Output $/M | $20 | $0.08 |
| Weights | Proprietary | Open |

## Coding

- Claude Opus 5.5: 71.4 (#1)
- Mistral Small 3: 36.0 (#203)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| LMArena Coding | 1545 | 1246 |
| FrontierCode | 54.4% | — |
| CursorBench | 57.8% | — |
| LMArena WebDev | 1820 | — |
| FrontierSWE | 62.3% | — |
| SciCode | 66.9% | — |
| BigCodeBench Instruct | — | 45.3% |
| MirrorCode | 77.4% | — |
| BigCodeBench Complete | — | 50.4% |

## Agentic & Tool Use

- Claude Opus 5.5: 45.3 (#13)
- Mistral Small 3: —

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| APEX-Agents | 73.5% | — |
| GDP.pdf | 30.6% | — |

## Reasoning

- Claude Opus 5.5: 79.5 (#2)
- Mistral Small 3: 18.2 (#269)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| LMArena Hard Prompts | 1545 | 1233 |
| ARC-AGI-2 | 92.5% | — |
| NYT Connections (extended) | 88.5% | — |
| ARC-AGI-1 | 97.5% | — |
| CritPt | 31.7% | — |
| Chess Puzzles | — | 0% |
| EBR-Bench | 71.4% | — |
| Mystery Game Puzzles | 71% | — |
| DTBench | 98.9% | — |
| LMCA | 68.2% | — |
| Epoch Capabilities Index | — | 127.06 |

## Math

- Claude Opus 5.5: 92.4 (#2)
- Mistral Small 3: 15.3 (#290)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 100% | 6.7% |
| FrontierMath (Tiers 1-3) | 91.2% | — |
| FrontierMath Tier 4 | 95% | — |
| ProofBench | 100% | — |
| LMArena Math | — | 1240 |

## Knowledge

- Claude Opus 5.5: 66.6 (#9)
- Mistral Small 3: 25.0 (#258)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| GPQA Diamond | 90.6% | 47.3% |
| LMArena Expert | 1564 | 1202 |
| SimpleQA Verified | 72.2% | — |
| Confabulations | — | 25.2% |

## Multimodal

- Claude Opus 5.5: 56.5 (#2)
- Mistral Small 3: —

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| Furniture Assembly | 83.3% | — |

## Multilingual

- Claude Opus 5.5: 59.8 (#1)
- Mistral Small 3: 37.5 (#231)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| LMArena Non-English | 1513 | 1198 |
| LMArena Chinese | 1572 | 1204 |
| LMArena Russian | 1532 | 1216 |
| LMArena French | — | 1202 |
| LMArena German | — | 1211 |
| LMArena Japanese | — | 1111 |
| LMArena Korean | — | 1188 |

## Instruction Following

- Claude Opus 5.5: 80.1 (#2)
- Mistral Small 3: 63.9 (#224)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| LMArena Instruction Following | 1535 | 1214 |

## Long Context

- Claude Opus 5.5: 47.3 (#18)
- Mistral Small 3: 37.8 (#206)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| LMArena Longer Query | 1540 | 1246 |

## Writing & Preference

- Claude Opus 5.5: 78.7 (#3)
- Mistral Small 3: 32.4 (#275)

| Benchmark | Claude Opus 5.5 | Mistral Small 3 |
|---|---|---|
| LMArena Text | 1518 | 1234 |
| LMArena Creative Writing | 1538 | 1195 |
| EQ-Bench Creative Writing | 2050 | 707 |
| LMArena Multi-Turn | 1520 | 1217 |

## FAQ

### Is Claude Opus 5.5 better than Mistral Small 3?

Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 30.9 on the Noometry Index. Mistral Small 3 costs 139× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

### Which is cheaper, Claude Opus 5.5 or Mistral Small 3?

Mistral Small 3 is cheaper. It lists at $0.05 per million input tokens and $0.08 per million output tokens; Claude Opus 5.5 lists at $4 and $20.

### Is Claude Opus 5.5 or Mistral Small 3 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.4 versus 36.0 in the Noometry coding category.

### Which has the bigger context window?

Claude Opus 5.5 does, with 1M tokens against 33K.

### How many benchmarks do Claude Opus 5.5 and Mistral Small 3 share?

14 benchmarks have published results for both models. Claude Opus 5.5 has 35 scored results on Noometry and Mistral Small 3 has 24.