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GoogleGemini 2.5 FlashVSOpenAIGPT-5.4

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

Our Take

We recommend GPT-5.4 if you need peak intelligence for complex complex codebases, multi-file repositories, and architectural planning, or the 6.6x cheaper Gemini 2.5 Flash if your workflow is limited to multi-file code and clearly defined tasks. While GPT-5.4 holds a major reasoning advantage, Gemini 2.5 Flash is optimized for high-volume budget pipelines. Choose GPT-5.4 for architectural codebase planning, or Gemini 2.5 Flash to maximize your budget for basic scripts.
WHY?
Benchmark Calculations & Evidence:
  • Coding Evaluation: Gemini 2.5 Flash was evaluated on SWE-bench Verified (scoring 60.4%), while GPT-5.4 was evaluated on SWE-bench Pro (scoring 57.7%).
  • Reasoning Accuracy: Both models were evaluated on the GPQA Diamond benchmark. GPT-5.4 scored 92.8%, while Gemini 2.5 Flash scored 68.3%.
  • Cost Efficiency: Gemini 2.5 Flash pricing ($0.3/M input, $2.5/M output) is 6.6x cheaper than GPT-5.4 ($2.5/M input, $15/M output).
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    Model Specs

    Gemini 2.5 Flash

    Benchmarks & Scores

    Coding (swe-bench-verified)
    60.4%

    multi-file code and clearly defined tasks

    Reasoning (gpqa-diamond)
    68.3%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)6.6x cheaper
    $0.85Input: $0.30 | Output: $2.50
    Context Window
    1.05M tokens
    Model Specs

    GPT-5.4

    Benchmarks & Scores

    Coding (swe-bench-pro)
    57.7%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)Winner (+24.5%)
    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 2.5 Flash vs GPT-5.4

    Gemini 2.5 Flash is cheaper than GPT-5.4. Gemini 2.5 Flash has a blended cost of $0.85/1M tokens, which is about 6.6x cheaper than GPT-5.4 at $5.63/1M tokens.

    For coding tasks, Gemini 2.5 Flash scores 60.4% on swe-bench-verified (multi-file code and clearly defined tasks), while GPT-5.4 scores 57.7% on swe-bench-pro (complex codebases, multi-file repositories, and architectural planning).

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