GPT-OSS 120B vs Gemini 3 Flash
Detailed comparison between GPT-OSS 120B and Gemini 3 Flash for RAG applications. See which LLM best meets your accuracy, performance, and cost needs.
Model Comparison
Gemini 3 Flash takes the lead.
Both GPT-OSS 120B and Gemini 3 Flash are powerful language models designed for RAG applications. However, their performance characteristics differ in important ways.
Why Gemini 3 Flash:
- Gemini 3 Flash has 304 higher ELO rating
- Gemini 3 Flash delivers better overall quality (4.95 vs 4.85)
- Gemini 3 Flash is 3.4s faster on average
- Gemini 3 Flash has a 43.1% higher win rate
Overview
Key metrics
ELO Rating
Overall ranking quality
GPT-OSS 120B
Gemini 3 Flash
Win Rate
Head-to-head performance
GPT-OSS 120B
Gemini 3 Flash
Quality Score
Overall quality metric
GPT-OSS 120B
Gemini 3 Flash
Average Latency
Response time
GPT-OSS 120B
Gemini 3 Flash
Visual Performance Analysis
Performance
ELO Rating Comparison
Win/Loss/Tie Breakdown
Quality Across Datasets (Overall Score)
Latency Distribution (ms)
Breakdown
How the models stack up
| Metric | GPT-OSS 120B | Gemini 3 Flash | Description |
|---|---|---|---|
| Overall Performance | |||
| ELO Rating | 1303 | 1607 | Overall ranking quality based on pairwise comparisons |
| Win Rate | 17.9% | 61.0% | Percentage of comparisons won against other models |
| Quality Score | 4.85 | 4.95 | Average quality across all RAG metrics |
| Pricing & Context | |||
| Input Price per 1M | $0.04 | $0.50 | Cost per million input tokens |
| Output Price per 1M | $0.19 | $3.00 | Cost per million output tokens |
| Context Window | 131K | 1049K | Maximum context window size |
| Release Date | 2025-08-05 | 2025-12-17 | Model release date |
| Performance Metrics | |||
| Avg Latency | 11.2s | 7.8s | Average response time across all datasets |
Dataset Performance
By benchmark
Comprehensive comparison of RAG quality metrics (correctness, faithfulness, grounding, relevance, completeness) and latency for each benchmark dataset.
MSMARCO
| Metric | GPT-OSS 120B | Gemini 3 Flash | Description |
|---|---|---|---|
| Quality Metrics | |||
| Correctness | 4.93 | 4.83 | Factual accuracy of responses |
| Faithfulness | 4.90 | 4.87 | Adherence to source material |
| Grounding | 4.90 | 4.87 | Citations and context usage |
| Relevance | 4.97 | 5.00 | Query alignment and focus |
| Completeness | 4.80 | 4.90 | Coverage of all aspects |
| Overall | 4.90 | 4.89 | Average across all metrics |
| Latency Metrics | |||
| Mean | 5616ms | 6852ms | Average response time |
| Min | 1255ms | 3389ms | Fastest response time |
| Max | 20330ms | 9837ms | Slowest response time |
PG
| Metric | GPT-OSS 120B | Gemini 3 Flash | Description |
|---|---|---|---|
| Quality Metrics | |||
| Correctness | 4.87 | 5.00 | Factual accuracy of responses |
| Faithfulness | 4.87 | 5.00 | Adherence to source material |
| Grounding | 4.87 | 5.00 | Citations and context usage |
| Relevance | 4.90 | 5.00 | Query alignment and focus |
| Completeness | 4.83 | 5.00 | Coverage of all aspects |
| Overall | 4.87 | 5.00 | Average across all metrics |
| Latency Metrics | |||
| Mean | 19128ms | 9444ms | Average response time |
| Min | 1317ms | 5346ms | Fastest response time |
| Max | 69491ms | 12549ms | Slowest response time |
SciFact
| Metric | GPT-OSS 120B | Gemini 3 Flash | Description |
|---|---|---|---|
| Quality Metrics | |||
| Correctness | 4.80 | 5.00 | Factual accuracy of responses |
| Faithfulness | 4.87 | 5.00 | Adherence to source material |
| Grounding | 4.87 | 5.00 | Citations and context usage |
| Relevance | 4.77 | 4.97 | Query alignment and focus |
| Completeness | 4.67 | 4.83 | Coverage of all aspects |
| Overall | 4.79 | 4.96 | Average across all metrics |
| Latency Metrics | |||
| Mean | 8854ms | 7110ms | Average response time |
| Min | 0ms | 3784ms | Fastest response time |
| Max | 35709ms | 18224ms | Slowest response time |
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