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GoogleGemini 3.5 FlashVSZ.ai (Zhipu AI)GLM-5.1

Analysis by:the whichllmmodel Editorial Team|Updated: June 2026

Our Take

We recommend GLM-5.1 for a 1.6x API cost saving and superior coding capability, or Gemini 3.5 Flash if your workflow requires peak reasoning. While GLM-5.1 is more cost-effective, Gemini 3.5 Flash holds a clear reasoning advantage. Choose GLM-5.1 for code generation, or Gemini 3.5 Flash for complex logical reasoning.
▶WHY?
Benchmark Calculations & Evidence:
  • Coding Benchmarks: Both models were evaluated on the SWE-bench Pro benchmark. Gemini 3.5 Flash scored 55.1%, while GLM-5.1 scored 58.4%.
  • Reasoning Benchmarks: Both models were evaluated on the GPQA Diamond benchmark. Gemini 3.5 Flash scored 92.2%, while GLM-5.1 scored 86.2%.
  • Cost Efficiency: GLM-5.1 pricing ($1.4/M input, $4.4/M output) is 1.6x cheaper than Gemini 3.5 Flash ($1.5/M input, $9/M output).
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    Model Specs

    Gemini 3.5 Flash

    Website

    Benchmarks & Scores

    Coding (swe-bench-pro)
    55.1%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)Winner (+6.0%)
    92.2%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)
    $3.38Input: $1.50 | Output: $9.00
    Context WindowLarger
    1.05M tokens
    Model Specs

    GLM-5.1

    Open SourceAPI Available
    Website🤗HF

    Benchmarks & Scores

    Coding (swe-bench-pro)Winner (+3.3%)
    58.4%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)
    86.2%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)1.6x cheaper
    $2.15Input: $1.40 | Output: $4.40
    Context Window
    202.75k tokens
    Read our data collection methodology

    Frequently Asked Questions about Gemini 3.5 Flash vs GLM-5.1

    GLM-5.1 is cheaper than Gemini 3.5 Flash. GLM-5.1 has a blended cost of $2.15/1M tokens, which is about 1.6x cheaper than Gemini 3.5 Flash at $3.38/1M tokens.

    GLM-5.1 is better for coding tasks on this benchmark. It scores 58.4% on swe-bench-pro (complex codebases, multi-file repositories, and architectural planning) compared to Gemini 3.5 Flash which scores 55.1%.

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