InternLM 2.5 20B vs Perplexity Sonar Pro

Compare InternLM 2.5 20B and Perplexity Sonar Pro: 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 InternLM 2.5 20B Perplexity Sonar Pro
CategoryOpen SourceSearch
Parameters20B~200B
Context Window256K200K
Input Price$0.02/1M tokens$0.003/1M tokens
Output Price$0.04/1M tokens$0.015/1M tokens
Latency~180ms~600ms

Choose InternLM 2.5 20B when:

  • ✓ Long context tasks
  • ✓ Research
  • ✓ Multilingual
Key Strengths:

256K context, Strong reasoning, Good multilingual

Choose Perplexity Sonar Pro when:

  • ✓ Research Q&A
  • ✓ Fact-checking
  • ✓ Current events
Key Strengths:

Web-grounded, Auto-citations, Current information

Verdict: InternLM 2.5 20B vs Perplexity Sonar Pro

For cost efficiency, Perplexity Sonar Pro wins at $0.003/1M input tokens. For speed, InternLM 2.5 20B is faster at ~180ms. InternLM 2.5 20B excels at Long context tasks while Perplexity Sonar Pro is better for Research Q&A. Both are available on XALEN through a single API — try them in the Playground to see which fits your workload.

Detailed Analysis

Pricing Comparison

InternLM 2.5 20B costs $0.02/1M input tokens and $0.04/1M output tokens. Perplexity Sonar Pro costs $0.003 input and $0.015 output. Perplexity Sonar Pro is 6.7x cheaper on input tokens. XALEN offers batch processing at 50% discount on both models.

Performance & Context

InternLM 2.5 20B has a 256K context window with ~180ms latency. Perplexity Sonar Pro offers 200K context at ~600ms. InternLM 2.5 20B has the larger context window.

Best For

InternLM 2.5 20B (Open Source) is optimized for: Long context tasks, Research, Multilingual. Perplexity Sonar Pro (Search) works best for: Research Q&A, Fact-checking, Current events.

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 InternLM 2.5 20B
response_a = client.chat.completions.create(
    model="internlm-2-5-20b",
    messages=[{"role": "user", "content": "Your question here"}]
)

# Use Perplexity Sonar Pro
response_b = client.chat.completions.create(
    model="perplexity-sonar-pro",
    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, InternLM 2.5 20B or Perplexity Sonar Pro?

InternLM 2.5 20B (Open Source, 20B) offers 256K context. Perplexity Sonar Pro (Search, ~200B) offers Web-grounded. Choose InternLM 2.5 20B for Long context tasks or Perplexity Sonar Pro for Research Q&A.

How much does InternLM 2.5 20B cost vs Perplexity Sonar Pro?

InternLM 2.5 20B: $0.02/1M input, $0.04/1M output. Perplexity Sonar Pro: $0.003/1M input, $0.015/1M 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 InternLM 2.5 20B and Perplexity Sonar Pro 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.