Llama 3.1 405B vs OpenAI o4-mini

Compare Llama 3.1 405B by Meta AI against OpenAI o4-mini by OpenAI, tested across 6 shared challenges. Updated April 2026.

Which is better, Llama 3.1 405B or OpenAI o4-mini?

Llama 3.1 405B and OpenAI o4-mini are both competitive models. Llama 3.1 405B costs $2.7/M input tokens vs $1.1/M for OpenAI o4-mini. Compare their real outputs side by side below.

Key Differences Between Llama 3.1 405B and OpenAI o4-mini

Llama 3.1 405B is made by meta while OpenAI o4-mini is from openai. On pricing, Llama 3.1 405B costs $2.7/M input tokens vs $1.1/M for OpenAI o4-mini.

Our Verdict
Llama 3.1 405B
Llama 3.1 405B
OpenAI o4-mini
OpenAI o4-mini

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call
Writing DNA

Style Comparison

Similarity
81%

Llama 3.1 405B uses 2.9x more emoji

Llama 3.1 405B
OpenAI o4-mini
56%Vocabulary73%
15wSentence Length15w
0.41Hedging0.18
0.0Bold0.0
1.9Lists2.1
0.03Emoji0.00
0.00Headings0.00
0.16Transitions0.02
Based on 5 + 10 text responses
vs

Ask them anything yourself

Llama 3.1 405BOpenAI 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