---
license: cc-by-nc-4.0
language:
- en
base_model:
- Qwen/Qwen3-4B
pipeline_tag: text-ranking
tags:
- finance
- legal
- code
- stem
- medical
---
# zerank-1-small: Smaller, faster version of zerank-1

<!-- Provide a quick summary of what the model is/does. -->


This model is the smaller version of [zeroentropy/zerank-1](https://huggingface.co/zeroentropy/zerank-1). Though the model is over 2x smaller, it maintains nearly the same standard of performance, continuing to outperform other popular rerankers.

It is an open-weights reranker model meant to be integrated into RAG applications to rerank results from preliminary search methods such as embeddings, BM25, and hybrid search.



## How to Use

```python
from sentence_transformers import CrossEncoder

model = CrossEncoder("zeroentropy/zerank-1-small", trust_remote_code=True)

query_documents = [
    ("What is 2+2?", "4"),
    ("What is 2+2?", "The answer is definitely 1 million"),
]

scores = model.predict(query_documents)

print(scores)
```

## Evaluations

Comparing NDCG@10 starting from top 100 documents by embedding (using text-3-embedding-small):

| Task           | Embedding | cohere-rerank-v3.5 | Salesforce/Llama-rank-v1 | **zerank-1-small** | zerank-1 |
|----------------|-----------|--------------------|--------------------------|----------------|----------|
| Code           |    0.678  |       0.724        |           0.694          |      **0.730**     |   0.754  |
| Conversational |    0.250  |       0.571        |           0.484          |      **0.556**     |   0.596  |
| Finance        |    0.839  |       0.824        |           0.828          |      **0.861**     |   0.894  |
| Legal          |    0.703  |       0.804        |           0.767          |      **0.817**     |   0.821  |
| Medical        |    0.619  |       0.750        |           0.719          |      **0.773**     |   0.796  |
| STEM           |    0.401  |       0.510        |           0.595          |      **0.680**     |   0.694  |

Comparing BM25 and Hybrid Search without and with zerank-1:

<img src="https://cdn-uploads.huggingface.co/production/uploads/67776f9dcd9c9435499eafc8/2GPVHFrI39FspnSNklhsM.png" alt="Description" width="400"/> <img src="https://cdn-uploads.huggingface.co/production/uploads/67776f9dcd9c9435499eafc8/dwYo2D7hoL8QiE8u3yqr9.png" alt="Description" width="400"/>


## Citation

**BibTeX:**

Coming soon!

**APA:**

Coming soon!