GPT OSS 20B vs o1-pro
GPT OSS 20B and o1-pro are closely matched at 17.9 and 19.7 on the LLM Stats Score.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT OSS 20B and o1-pro are closely matched on the overall LLM Stats Score at 17.9 and 19.7.
In the 1 individual benchmarks reported for both models, o1-pro wins 1; this is a narrower head-to-head signal than the composite indexes.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT OSS 20B
- you want the most recent training data — it shipped Aug 2025
- you need open weights you can self-host or fine-tune
Choose o1-pro
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
At a glance
The differences that matter most.
Individual benchmarks
7 reported for GPT OSS 20B · 2 for o1-pro
GPT OSS 20B outperforms in 0 benchmarks, while o1-pro is better at 1 benchmark (GPQA).
o1-pro significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Context Window
Maximum input and output token capacity
Only GPT OSS 20B specifies input context (131,072 tokens). Only GPT OSS 20B specifies output context (131,072 tokens).
Input capabilities
Documented input modalities across available providers
o1-pro supports multimodal inputs, whereas GPT OSS 20B does not.
o1-pro can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT OSS 20B
o1-pro
License
Usage and distribution terms
GPT OSS 20B is licensed under Apache 2.0, while o1-pro uses a proprietary license.
License differences may affect how you can use these models in commercial or open-source projects.
Apache 2.0
Open weights
Proprietary
Closed source
Release Timeline
When each model was launched
GPT OSS 20B was released on 2025-08-05, while o1-pro was released on 2024-12-17.
GPT OSS 20B is 8 months newer than o1-pro.
Aug 5, 2025
1.1 years ago
7mo newerDec 17, 2024
1.8 years ago
Knowledge Cutoff
When training data ends
o1-pro has a documented knowledge cutoff of 2023-09-30, while GPT OSS 20B's cutoff date is not specified.
We can confirm o1-pro's training data extends to 2023-09-30, but cannot make a direct comparison without GPT OSS 20B's cutoff date.
—
Sep 2023
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT OSS 20B and o1-pro side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT OSS 20B vs o1-pro.