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GoogleGemini 3.5 FlashVSOpenAIGPT-5.4

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

Our Take

We recommend Gemini 3.5 Flash for a 1.7x API cost saving at identical performance levels. While both models deliver similar intelligence, Gemini 3.5 Flash is the optimal choice for high-volume pipelines. Choose Gemini 3.5 Flash for budget efficiency without sacrificing quality.
WHY?
Benchmark Calculations & Evidence:
  • Performance Match: Both models perform almost identically, with an average score gap of just 1.6% across reasoning and coding benchmarks.
  • Coding Benchmarks: Both models were evaluated on the SWE-bench Pro benchmark. Gemini 3.5 Flash scored 55.1%, while GPT-5.4 scored 57.7%.
  • Reasoning Benchmarks: Both models were evaluated on the GPQA Diamond benchmark. Gemini 3.5 Flash scored 92.2%, while GPT-5.4 scored 92.8%.
  • Cost Efficiency: Gemini 3.5 Flash pricing ($1.5/M input, $9/M output) is 1.7x cheaper than GPT-5.4 ($2.5/M input, $15/M output).
  • Was this recommendation helpful?
    Model Specs

    Gemini 3.5 Flash

    Benchmarks & Scores

    Coding (swe-bench-pro)
    55.1%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)
    92.2%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)1.7x cheaper
    $3.38Input: $1.50 | Output: $9.00
    Context Window
    1.05M tokens
    Model Specs

    GPT-5.4

    Benchmarks & Scores

    Coding (swe-bench-pro)Winner (+2.6%)
    57.7%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)Winner (+0.6%)
    92.8%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)
    $5.63Input: $2.50 | Output: $15.00
    Context WindowLarger
    1.05M tokens

    Frequently Asked Questions about Gemini 3.5 Flash vs GPT-5.4

    Gemini 3.5 Flash is cheaper than GPT-5.4. Gemini 3.5 Flash has a blended cost of $3.38/1M tokens, which is about 1.7x cheaper than GPT-5.4 at $5.63/1M tokens.

    GPT-5.4 is better for coding tasks on this benchmark. It scores 57.7% 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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