GPT-4.1 nano vs GPT OSS 20B
GPT OSS 20B significantly outperforms across most benchmarks. GPT OSS 20B is 2.0x cheaper per token.
OpenAI · OpenAI · Updated for 2026
Which is better?
GPT-4.1 nano outperforms in 0 benchmarks, while GPT OSS 20B is better at 3 benchmarks (GPQA, MMLU, TAU-bench Retail). GPT OSS 20B significantly outperforms across most benchmarks.
On price, GPT OSS 20B is roughly 2.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-4.1 nano also accepts a larger context window (1,047,576 input tokens), making it the stronger choice for long documents and large codebases.
Based on current benchmark, pricing, and model metadata for 2026.
Choose GPT-4.1 nano
- you process long inputs — it offers a 1,047,576 token context window
Choose GPT OSS 20B
- you want the strongest raw capability — it leads on 3 of 3 shared benchmarks
- cost matters — it's about 2.0x cheaper per token
- 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.
Performance Benchmarks
Comparative analysis across standard metrics
GPT-4.1 nano outperforms in 0 benchmarks, while GPT OSS 20B is better at 3 benchmarks (GPQA, MMLU, TAU-bench Retail).
GPT OSS 20B significantly outperforms across most benchmarks.
Arena Performance
Playground indexes and blind preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-4.1 nano ($0.10/1M tokens) is 2.0x more expensive than GPT OSS 20B ($0.05/1M tokens).
For output processing, GPT-4.1 nano ($0.40/1M tokens) is 2.0x more expensive than GPT OSS 20B ($0.20/1M tokens).
In conclusion, GPT-4.1 nano 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-4.1 nano accepts 1,047,576 input tokens compared to GPT OSS 20B's 131,072 tokens. Both models can generate responses up to 32,768 tokens.
Input Capabilities
Supported data types and modalities
GPT-4.1 nano supports multimodal inputs, whereas GPT OSS 20B does not.
GPT-4.1 nano can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-4.1 nano
GPT OSS 20B
License
Usage and distribution terms
GPT-4.1 nano 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-4.1 nano was released on 2025-04-14, while GPT OSS 20B was released on 2025-08-05.
GPT OSS 20B is 4 months newer than GPT-4.1 nano.
Apr 14, 2025
1.4 years ago
Aug 5, 2025
1.1 years ago
3mo newerKnowledge Cutoff
When training data ends
GPT-4.1 nano has a documented knowledge cutoff of 2024-05-31, while GPT OSS 20B's cutoff date is not specified.
We can confirm GPT-4.1 nano's training data extends to 2024-05-31, but cannot make a direct comparison without GPT OSS 20B's cutoff date.
May 2024
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Provider Availability
GPT-4.1 nano is available from OpenAI. GPT OSS 20B is available from Novita, Fireworks, Groq, OpenAI.
GPT-4.1 nano
GPT OSS 20B
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-4.1 nano and GPT OSS 20B side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-4.1 nano vs GPT OSS 20B.