Llama 3.1 405B vs Phi-4

Compare Llama 3.1 405B and Phi-4: pricing, performance, context window, latency, and best use cases. Side-by-side comparison on XALEN.

Updated 2026-05-21 · By Abhishek Raj · Our methodology

All Meta models All Microsoft models What is an LLM API? Python Quickstart What is inference?
Feature Llama 3.1 405B Phi-4
CategoryOpen SourceCompact
Parameters405B14B
Context Window128K16K
Input Price$0.08/1M tokens$0.01/1M tokens
Output Price$0.14/1M tokens$0.02/1M tokens
Latency~600ms~100ms

Choose Llama 3.1 405B when:

  • ✓ Premium tasks
  • ✓ Research
  • ✓ Fine-tuning base
Key Strengths:

Largest open model, Highest open-source quality

Choose Phi-4 when:

  • ✓ Edge deployments
  • ✓ Cost-sensitive apps
  • ✓ Classification
Key Strengths:

Very compact, Strong reasoning for size, Extremely low cost

Verdict: Llama 3.1 405B vs Phi-4

For cost efficiency, Phi-4 wins at $0.01/1M input tokens. For speed, Phi-4 is faster at ~100ms. Llama 3.1 405B excels at Premium tasks while Phi-4 is better for Edge deployments. Both are available on XALEN through a single API — try them in the Playground to see which fits your workload.

Detailed Analysis

Pricing Comparison

Llama 3.1 405B costs $0.08/1M input tokens and $0.14/1M output tokens. Phi-4 costs $0.01 input and $0.02 output. Phi-4 is 8.0x cheaper on input tokens. XALEN offers batch processing at 50% discount on both models.

Performance & Context

Llama 3.1 405B has a 128K context window with ~600ms latency. Phi-4 offers 16K context at ~100ms. Llama 3.1 405B has the larger context window.

Best For

Llama 3.1 405B (Open Source) is optimized for: Premium tasks, Research, Fine-tuning base. Phi-4 (Compact) works best for: Edge deployments, Cost-sensitive apps, Classification.

Try Both on XALEN

Both models are available through XALEN's OpenAI-compatible API. Switch between them by changing the model parameter:

from xalen import XALEN

client = XALEN(api_key="xln_test_YOUR_KEY")

# Use Llama 3.1 405B
response_a = client.chat.completions.create(
    model="llama-3-1-405b",
    messages=[{"role": "user", "content": "Your question here"}]
)

# Use Phi-4
response_b = client.chat.completions.create(
    model="phi-4",
    messages=[{"role": "user", "content": "Your question here"}]
)

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Get API Key Try in Playground

Frequently Asked Questions

Which is better, Llama 3.1 405B or Phi-4?

Llama 3.1 405B (Open Source, 405B) offers Largest open model. Phi-4 (Compact, 14B) offers Very compact. Choose Llama 3.1 405B for Premium tasks or Phi-4 for Edge deployments.

How much does Llama 3.1 405B cost vs Phi-4?

Llama 3.1 405B: $0.08/1M input, $0.14/1M output. Phi-4: $0.01/1M input, $0.02/1M output. Both available on XALEN with batch processing at 50% discount.

Can I use both models on XALEN?

Yes. XALEN provides 200+ models through a single OpenAI-compatible API. Switch between Llama 3.1 405B and Phi-4 by changing the model parameter. No code changes needed.

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Last updated: 2026-05-21. Pricing and specifications may change. Check pricing page for latest rates.