Llama 3.1 8B VS ChatGPT-4o mini

2025-12-20

In the rapidly evolving landscape of Large Language Models (LLMs), choosing between a powerful open-source model and a high-efficiency proprietary one is a common challenge. This analysis provides a deep dive into the Llama 3.1 8B vs. GPT-4o mini comparison, exploring their technical specifications, standardized benchmarks, and real-world performance.

Core Specifications & Hardware Efficiency

When analyzing lightweight AI models, small differences in base specs can lead to significant shifts in deployment costs and user experience. Based on the original analysis in Benchmarks and specs, here is how they stack up:

Specification Llama 3.1 8B ChatGPT-4o mini
Context Window 128K 128K
Max Output Tokens 4K 16K
Knowledge Cutoff Dec 2023 Oct 2023
Speed (Tokens/sec) ~147 ~99

💡 Key Insight: While GPT-4o mini supports longer generation (16K output), Llama 3.1 8B is significantly faster in processing speed, making it ideal for real-time applications where latency is critical.

Industry Standard Benchmarks

Benchmarks provide a standardized way to measure "intelligence" across reasoning, math, and coding. GPT-4o mini generally maintains a lead in cognitive heavy-lifting.

Benchmark Category Llama 3.1 8B GPT-4o mini
MMLU (General Knowledge) 73.0 82.0
HumanEval (Coding) 72.6 87.2
MATH (Advanced Math) 51.9 70.2

Real-World Performance Testing

🧩 Test Case: Logical Reasoning (The "Zorks & Yorks" Puzzle)

Prompt: If all Zorks are Yorks, and some Yorks are Sporks, can we conclude that some Zorks are definitely Sporks?

Llama 3.1 8B: ❌ Failed

Incorrectly used transitive reasoning to claim a definite connection between Zorks and Sporks.

GPT-4o mini: ✅ Passed

Correctly identified that an overlap between Yorks and Sporks does not guarantee an overlap with the Zork subset.

💻 Test Case: Python Game Development (Arkanoid)

We challenged both models to generate a fully functional Pygame module with specific UI and logic requirements.

  • 🚀 GPT-4o mini: Produced clean, well-commented, and runnable code that met all 10 feature requirements.
  • ⚠️ Llama 3.1 8B: Struggled with complex logic integration, resulting in code that required manual debugging to function.

Pricing & Cost Efficiency

Cost is often the deciding factor for high-volume applications. While input costs are comparable, Llama 3.1 offers better scalability for long-form generation.

Model Input (per 1K tokens) Output (per 1K tokens)
Llama 3.1 8B $0.000234 $0.000234
GPT-4o mini $0.000195 $0.0009

Final Verdict: Which Should You Choose?

Choose GPT-4o mini if:

  • You need complex reasoning and high coding accuracy.
  • You require long output lengths (up to 16K tokens).
  • You want a highly versatile model for diverse, "smart" agent tasks.

Choose Llama 3.1 8B if:

  • Speed and latency are your top priorities.
  • You are focused on cost optimization for output tokens.
  • You prefer an open-weights ecosystem with high processing throughput.

Frequently Asked Questions


Q1: Which model is better for coding?
A: GPT-4o mini is significantly more capable at coding, scoring 87.2 on HumanEval compared to Llama 3.1 8B's 72.6.

Q2: Is Llama 3.1 8B faster than GPT-4o mini?
A: Yes, in many benchmark environments, Llama 3.1 8B achieves roughly 147 tokens per second, which is about 48% faster than GPT-4o mini's ~99 tokens per second.

Q3: Can these models handle large documents?
A: Both models feature a 128K context window, making them equally capable of "reading" large files, though GPT-4o mini can "write" longer responses.

Q4: Why is Llama 3.1 8B cheaper for output?
A: Llama 3.1 8B is an open-source architecture designed for efficiency. Many providers offer lower output pricing (up to 4x cheaper) compared to GPT-4o mini.