Model Comparison
GPT-5.3 Chat vs GPT OSS 120BWhich is better in 2026?
GPT OSS 120B significantly outperforms across most benchmarks. GPT OSS 120B is 26.7x cheaper per token.
Verdict: GPT-5.3 Chat vs GPT OSS 120B — which is better?
GPT-5.3 Chat (by OpenAI) and GPT OSS 120B (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
GPT-5.3 Chat outperforms in 0 benchmarks, while GPT OSS 120B is better at 2 benchmarks (HealthBench, HealthBench Hard). GPT OSS 120B significantly outperforms across most benchmarks.
On price, GPT OSS 120B is roughly 26.7x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT OSS 120B also accepts a larger context window (131,072 input tokens), making it the stronger choice for long documents and large codebases.
Choose GPT-5.3 Chat if…
- you want the most recent training data — it shipped Mar 2026
Choose GPT OSS 120B if…
- you want the strongest raw capability — it leads on 2 of 2 shared benchmarks
- cost matters — it's about 26.7x cheaper per token
- you process long inputs — it offers a 131,072 token context window
- you need open weights you can self-host or fine-tune
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.3 Chat outperforms in 0 benchmarks, while GPT OSS 120B is better at 2 benchmarks (HealthBench, HealthBench Hard).
GPT OSS 120B significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.3 Chat ($1.75/1M tokens) is 19.4x more expensive than GPT OSS 120B ($0.09/1M tokens).
For output processing, GPT-5.3 Chat ($14.00/1M tokens) is 31.1x more expensive than GPT OSS 120B ($0.45/1M tokens).
In conclusion, GPT-5.3 Chat is more expensive than GPT OSS 120B.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT OSS 120B accepts 131,072 input tokens compared to GPT-5.3 Chat's 128,000 tokens. GPT OSS 120B can generate longer responses up to 131,072 tokens, while GPT-5.3 Chat is limited to 16,384 tokens.
Input Capabilities
Supported data types and modalities
GPT-5.3 Chat supports multimodal inputs, whereas GPT OSS 120B does not.
GPT-5.3 Chat can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-5.3 Chat
GPT OSS 120B
License
Usage and distribution terms
GPT-5.3 Chat is licensed under a proprietary license, while GPT OSS 120B 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-5.3 Chat was released on 2026-03-04, while GPT OSS 120B was released on 2025-08-05.
GPT-5.3 Chat is 7 months newer than GPT OSS 120B.
Mar 4, 2026
4 months ago
7mo newerAug 5, 2025
11 months ago
Knowledge Cutoff
When training data ends
GPT-5.3 Chat has a documented knowledge cutoff of 2025-08-31, while GPT OSS 120B's cutoff date is not specified.
We can confirm GPT-5.3 Chat's training data extends to 2025-08-31, but cannot make a direct comparison without GPT OSS 120B's cutoff date.
Aug 2025
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Provider Availability
GPT-5.3 Chat is available from OpenAI. GPT OSS 120B is available from DeepInfra, Novita, OpenAI, Fireworks, Groq.
GPT-5.3 Chat
GPT OSS 120B
Outputs Comparison
Key Takeaways
GPT-5.3 Chat
View detailsOpenAI
GPT OSS 120B
View detailsOpenAI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.3 Chat and GPT OSS 120B side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT-5.3 Chat vs GPT OSS 120B.