Llama 3.1 405B vs SD 3.5 Medium

Compare Llama 3.1 405B and SD 3.5 Medium: pricing, performance, context window, latency, and best use cases. Side-by-side comparison on XALEN.

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

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Feature Llama 3.1 405B SD 3.5 Medium
CategoryOpen SourceImage
Parameters405B2.5B
Context Window128KN/A
Input Price$0.08/1M tokens$0.003/image/1M tokens
Output Price$0.14/1M tokensN/A/1M tokens
Latency~600ms~2s

Choose Llama 3.1 405B when:

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

Largest open model, Highest open-source quality

Choose SD 3.5 Medium when:

  • ✓ General imagery
  • ✓ Batch generation
  • ✓ Prototyping
Key Strengths:

Good quality, Fast, Open weights

Verdict: Llama 3.1 405B vs SD 3.5 Medium

For cost efficiency, SD 3.5 Medium wins at $0.003/image/1M input tokens. For speed, SD 3.5 Medium is faster at ~2s. Llama 3.1 405B excels at Premium tasks while SD 3.5 Medium is better for General imagery. 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. SD 3.5 Medium costs $0.003/image input and N/A output. SD 3.5 Medium is 26.7x 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. SD 3.5 Medium offers N/A context at ~2s. 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. SD 3.5 Medium (Image) works best for: General imagery, Batch generation, Prototyping.

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 SD 3.5 Medium
response_b = client.chat.completions.create(
    model="stable-diffusion-3-5-medium",
    messages=[{"role": "user", "content": "Your question here"}]
)

Start Building with XALEN

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Get API Key Try in Playground

Frequently Asked Questions

Which is better, Llama 3.1 405B or SD 3.5 Medium?

Llama 3.1 405B (Open Source, 405B) offers Largest open model. SD 3.5 Medium (Image, 2.5B) offers Good quality. Choose Llama 3.1 405B for Premium tasks or SD 3.5 Medium for General imagery.

How much does Llama 3.1 405B cost vs SD 3.5 Medium?

Llama 3.1 405B: $0.08/1M input, $0.14/1M output. SD 3.5 Medium: $0.003/image/1M input, N/A/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 SD 3.5 Medium 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.