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AnthropicClaude Opus 5VSGoogleGemini 2.5 Flash

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

Our Take

We recommend Claude Opus 5 if you need peak intelligence for complex complex codebases, multi-file repositories, and architectural planning, or the 11.8x cheaper Gemini 2.5 Flash if your workflow is limited to multi-file code and clearly defined tasks. While Claude Opus 5 holds a major reasoning advantage, Gemini 2.5 Flash is optimized for high-volume budget pipelines. Choose Claude Opus 5 for architectural codebase planning, or Gemini 2.5 Flash to maximize your budget for basic scripts.
▶WHY?
Benchmark Calculations & Evidence:
  • Coding Evaluation: Claude Opus 5 was evaluated on SWE-bench Pro (scoring 79.2%), while Gemini 2.5 Flash was evaluated on SWE-bench Verified (scoring 60.4%).
  • Reasoning Accuracy: Both models were evaluated on the GPQA Diamond benchmark. Claude Opus 5 scored 93.7%, while Gemini 2.5 Flash scored 68.3%.
  • Cost Efficiency: Gemini 2.5 Flash pricing ($0.3/M input, $2.5/M output) is 11.8x cheaper than Claude Opus 5 ($5/M input, $25/M output).
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    Model Specs

    Claude Opus 5

    Website

    Benchmarks & Scores

    Coding (swe-bench-pro)
    79.2%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)Winner (+25.4%)
    93.7%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)
    $10.00Input: $5.00 | Output: $25.00
    Context Window
    1.05M tokens
    Model Specs

    Gemini 2.5 Flash

    Website

    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)11.8x cheaper
    $0.85Input: $0.30 | Output: $2.50
    Context Window
    1.05M tokens
    Read our data collection methodology

    Frequently Asked Questions about Claude Opus 5 vs Gemini 2.5 Flash

    Gemini 2.5 Flash is cheaper than Claude Opus 5. Gemini 2.5 Flash has a blended cost of $0.85/1M tokens, which is about 11.8x cheaper than Claude Opus 5 at $10.00/1M tokens.

    For coding tasks, Claude Opus 5 scores 79.2% on swe-bench-pro (complex codebases, multi-file repositories, and architectural planning), while Gemini 2.5 Flash scores 60.4% on swe-bench-verified (multi-file code and clearly defined tasks).

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