GPT OSS 120B vs OpenAI o4-mini

Compare GPT OSS 120B and OpenAI o4-mini, both from OpenAI, tested across 35 shared challenges. Updated April 2026.

Which is better, GPT OSS 120B or OpenAI o4-mini?

GPT OSS 120B and OpenAI o4-mini are both competitive models. GPT OSS 120B costs $0.18/M input tokens vs $1.1/M for OpenAI o4-mini. Compare their real outputs side by side below.

Key Differences Between GPT OSS 120B and OpenAI o4-mini

GPT OSS 120B is made by openai while OpenAI o4-mini is from openai. On pricing, GPT OSS 120B costs $0.18/M input tokens vs $1.1/M for OpenAI o4-mini.

Our Verdict
GPT OSS 120B
GPT OSS 120B
OpenAI o4-mini
OpenAI o4-miniRunner-up

No community votes yet. On paper, GPT OSS 120B has the edge — bigger model tier, newer, bigger context window.

GPT OSS 120B is 5.5x cheaper per token — worth considering if cost matters.

Too close to call
Writing DNA

Style Comparison

Similarity
94%

GPT OSS 120B uses 743.4x more bold

GPT OSS 120B
OpenAI o4-mini
52%Vocabulary73%
19wSentence Length15w
0.28Hedging0.18
7.4Bold0.0
1.8Lists2.1
0.15Emoji0.00
0.73Headings0.00
0.17Transitions0.02
Based on 21 + 10 text responses
vs

Ask them anything yourself

GPT OSS 120BOpenAI o4-mini

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026
Free preview13 of 58 slides
FAQ

Common questions