GPT-5.1 Medium vs GPT OSS 20B High
GPT-5.1 Medium and GPT OSS 20B High are closely matched at 31.2 and 27.6 on the LLM Stats Score. GPT OSS 20B High is 17.2x cheaper per token.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT-5.1 Medium and GPT OSS 20B High are closely matched on the overall LLM Stats Score at 31.2 and 27.6.
In the 1 individual benchmarks reported for both models, GPT OSS 20B High wins 1; this is a narrower head-to-head signal than the composite indexes.
On price, GPT OSS 20B High is roughly 17.2x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.1 Medium also accepts a larger context window (400,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5.1 Medium
- you process long inputs — it offers a 400,000 token context window
- you want the most recent training data — it shipped Nov 2025
Choose GPT OSS 20B High
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
- cost matters — it's about 17.2x cheaper per token
- you need open weights you can self-host or fine-tune
At a glance
The differences that matter most.
Individual benchmarks
1 reported for GPT-5.1 Medium · 2 for GPT OSS 20B High
GPT-5.1 Medium outperforms in 0 benchmarks, while GPT OSS 20B High is better at 1 benchmark (AIME 2025).
GPT OSS 20B High significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.1 Medium ($1.25/1M tokens) is 12.5x more expensive than GPT OSS 20B High ($0.10/1M tokens).
For output processing, GPT-5.1 Medium ($10.00/1M tokens) is 20.0x more expensive than GPT OSS 20B High ($0.50/1M tokens).
In conclusion, GPT-5.1 Medium is more expensive than GPT OSS 20B High.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.1 Medium accepts 400,000 input tokens compared to GPT OSS 20B High's 131,072 tokens. GPT OSS 20B High can generate longer responses up to 131,072 tokens, while GPT-5.1 Medium is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
GPT-5.1 Medium supports multimodal inputs, whereas GPT OSS 20B High does not.
GPT-5.1 Medium can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-5.1 Medium
GPT OSS 20B High
License
Usage and distribution terms
GPT-5.1 Medium is licensed under a proprietary license, while GPT OSS 20B High uses Apache 2.0.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
Apache 2.0
Open weights
Release Timeline
When each model was launched
GPT-5.1 Medium was released on 2025-11-12, while GPT OSS 20B High was released on 2025-08-05.
GPT-5.1 Medium is 3 months newer than GPT OSS 20B High.
Nov 12, 2025
11 months ago
3mo newerAug 5, 2025
1.2 years ago
Knowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
GPT-5.1 Medium is available from OpenAI. GPT OSS 20B High is available from OpenAI.
GPT-5.1 Medium
GPT OSS 20B High
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.1 Medium and GPT OSS 20B High side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.1 Medium vs GPT OSS 20B High.