GPT-4o mini vs GPT OSS 20B
GPT OSS 20B leads the LLM Stats Score 17.2 to 3.8. GPT OSS 20B is 3.0x cheaper per token.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT OSS 20B leads the overall LLM Stats Score 17.2 to 3.8, ranking #206 overall.
In the 2 individual benchmarks reported for both models, GPT OSS 20B wins 2; this is a narrower head-to-head signal than the composite indexes.
On price, GPT OSS 20B is roughly 3.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT OSS 20B also accepts a larger context window (131,072 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-4o mini
- you want predictable pricing at $0.15/M input and $0.60/M output
Choose GPT OSS 20B
- overall performance matters — it scores 17.2 and ranks #206 on LLM Stats
- your work emphasizes reasoning — it leads those capability indexes
- you value its reported benchmark strengths — it wins 2 of 2 exact shared results
- cost matters — it's about 3.0x cheaper per token
- you process long inputs — it offers a 131,072 token context window
- you want the most recent training data — it shipped Aug 2025
- you need open weights you can self-host or fine-tune
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
9 reported for GPT-4o mini · 7 for GPT OSS 20B
GPT-4o mini outperforms in 0 benchmarks, while GPT OSS 20B is better at 2 benchmarks (GPQA, MMLU).
GPT OSS 20B 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-4o mini ($0.15/1M tokens) is 3.0x more expensive than GPT OSS 20B ($0.05/1M tokens).
For output processing, GPT-4o mini ($0.60/1M tokens) is 3.0x more expensive than GPT OSS 20B ($0.20/1M tokens).
In conclusion, GPT-4o mini is more expensive than GPT OSS 20B.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT OSS 20B accepts 131,072 input tokens compared to GPT-4o mini's 128,000 tokens. GPT OSS 20B can generate longer responses up to 32,768 tokens, while GPT-4o mini is limited to 16,384 tokens.
Input capabilities
Documented input modalities across available providers
GPT-4o mini supports multimodal inputs, whereas GPT OSS 20B does not.
GPT-4o mini can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-4o mini
GPT OSS 20B
License
Usage and distribution terms
GPT-4o mini is licensed under a proprietary license, while GPT OSS 20B 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-4o mini was released on 2024-07-18, while GPT OSS 20B was released on 2025-08-05.
GPT OSS 20B is 13 months newer than GPT-4o mini.
Jul 18, 2024
2.1 years ago
Aug 5, 2025
1.1 years ago
1.0yr newerKnowledge Cutoff
When training data ends
GPT-4o mini has a documented knowledge cutoff of 2023-10-01, while GPT OSS 20B's cutoff date is not specified.
We can confirm GPT-4o mini's training data extends to 2023-10-01, but cannot make a direct comparison without GPT OSS 20B's cutoff date.
Oct 2023
—
Provider Availability
GPT-4o mini is available from Azure. GPT OSS 20B is available from Novita, Fireworks, Groq, OpenAI.
GPT-4o mini
GPT OSS 20B
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-4o mini and GPT OSS 20B side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-4o mini vs GPT OSS 20B.