Contextual AI Rerank v2 Instruct vs Zerank 1 Small
Detailed comparison between Contextual AI Rerank v2 Instruct and Zerank 1 Small. See which reranker best meets your accuracy and performance needs.
Model Comparison
Contextual AI Rerank v2 Instruct takes the lead.
Both Contextual AI Rerank v2 Instruct and Zerank 1 Small are powerful reranking models designed to improve retrieval quality in RAG applications. However, their performance characteristics differ in important ways.
Why Contextual AI Rerank v2 Instruct:
- Contextual AI Rerank v2 Instruct has 91 higher ELO rating
- Contextual AI Rerank v2 Instruct delivers better accuracy (nDCG@10: 0.687 vs 0.676)
- Zerank 1 Small is 1901ms faster on average
- Zerank 1 Small has a 10.9% higher win rate
Overview
Key metrics
ELO Rating
Overall ranking quality
Contextual AI Rerank v2 Instruct
Zerank 1 Small
Win Rate
Head-to-head performance
Contextual AI Rerank v2 Instruct
Zerank 1 Small
Accuracy (nDCG@10)
Ranking quality metric
Contextual AI Rerank v2 Instruct
Zerank 1 Small
Average Latency
Response time
Contextual AI Rerank v2 Instruct
Zerank 1 Small
Visual Performance Analysis
Performance
ELO Rating Comparison
Win/Loss/Tie Breakdown
Accuracy Across Datasets (nDCG@10)
Latency Distribution (ms)
Breakdown
How the models stack up
| Metric | Contextual AI Rerank v2 Instruct | Zerank 1 Small | Description |
|---|---|---|---|
| Overall Performance | |||
| ELO Rating | 1550 | 1458 | Overall ranking quality based on pairwise comparisons |
| Win Rate | 45.2% | 56.2% | Percentage of comparisons won against other models |
| Pricing & Availability | |||
| Price per 1M tokens | $0.050 | $0.025 | Cost per million tokens processed |
| Release Date | 2025-09-12 | 2025-07-10 | Model release date |
| Accuracy Metrics | |||
| Avg nDCG@10 | 0.687 | 0.676 | Normalized discounted cumulative gain at position 10 |
| Performance Metrics | |||
| Avg Latency | 3010ms | 1109ms | Average response time across all datasets |
Dataset Performance
By field
Comprehensive comparison of accuracy metrics (nDCG, Recall) and latency percentiles for each benchmark dataset.
FiQa
| Metric | Contextual AI Rerank v2 Instruct | Zerank 1 Small | Description |
|---|---|---|---|
| Accuracy Metrics | |||
| nDCG@5 | 0.119 | 0.114 | Ranking quality at top 5 results |
| nDCG@10 | 0.125 | 0.124 | Ranking quality at top 10 results |
| Recall@5 | 0.123 | 0.098 | % of relevant docs in top 5 |
| Recall@10 | 0.135 | 0.125 | % of relevant docs in top 10 |
| Latency Metrics | |||
| Mean | 2913ms | 969ms | Average response time |
| P50 | 2863ms | 977ms | 50th percentile (median) |
| P90 | 3289ms | 1086ms | 90th percentile |
SciFact
| Metric | Contextual AI Rerank v2 Instruct | Zerank 1 Small | Description |
|---|---|---|---|
| Accuracy Metrics | |||
| nDCG@5 | 0.867 | 0.869 | Ranking quality at top 5 results |
| nDCG@10 | 0.875 | 0.872 | Ranking quality at top 10 results |
| Recall@5 | 0.916 | 0.916 | % of relevant docs in top 5 |
| Recall@10 | 0.940 | 0.920 | % of relevant docs in top 10 |
| Latency Metrics | |||
| Mean | 3317ms | 1345ms | Average response time |
| P50 | 3198ms | 1272ms | 50th percentile (median) |
| P90 | 4004ms | 1552ms | 90th percentile |
PG
| Metric | Contextual AI Rerank v2 Instruct | Zerank 1 Small | Description |
|---|---|---|---|
| Accuracy Metrics | |||
| Latency Metrics | |||
| Mean | 3195ms | 1224ms | Average response time |
| P50 | 2951ms | 1187ms | 50th percentile (median) |
| P90 | 3781ms | 1307ms | 90th percentile |
business reports
| Metric | Contextual AI Rerank v2 Instruct | Zerank 1 Small | Description |
|---|---|---|---|
| Accuracy Metrics | |||
| Latency Metrics | |||
| Mean | 2883ms | 1051ms | Average response time |
| P50 | 2686ms | 1060ms | 50th percentile (median) |
| P90 | 3161ms | 1171ms | 90th percentile |
MSMARCO
| Metric | Contextual AI Rerank v2 Instruct | Zerank 1 Small | Description |
|---|---|---|---|
| Accuracy Metrics | |||
| nDCG@5 | 0.975 | 0.965 | Ranking quality at top 5 results |
| nDCG@10 | 0.975 | 0.968 | Ranking quality at top 10 results |
| Recall@5 | 1.000 | 0.987 | % of relevant docs in top 5 |
| Recall@10 | 1.000 | 0.993 | % of relevant docs in top 10 |
| Latency Metrics | |||
| Mean | 2952ms | 1014ms | Average response time |
| P50 | 2853ms | 1010ms | 50th percentile (median) |
| P90 | 3398ms | 1097ms | 90th percentile |
DBPedia
| Metric | Contextual AI Rerank v2 Instruct | Zerank 1 Small | Description |
|---|---|---|---|
| Accuracy Metrics | |||
| nDCG@5 | 0.734 | 0.683 | Ranking quality at top 5 results |
| nDCG@10 | 0.772 | 0.739 | Ranking quality at top 10 results |
| Recall@5 | 0.067 | 0.061 | % of relevant docs in top 5 |
| Recall@10 | 0.108 | 0.102 | % of relevant docs in top 10 |
| Latency Metrics | |||
| Mean | 2803ms | 1053ms | Average response time |
| P50 | 2786ms | 1034ms | 50th percentile (median) |
| P90 | 3138ms | 1170ms | 90th percentile |
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