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DeepSeekDeepSeek V4 ProVSOpenAIGPT-5.5

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

Our Take

We recommend GPT-5.5 if you need peak intelligence for reasoning and coding tasks, or the 5.2x cheaper DeepSeek V4 Pro to optimize your budget for high-volume pipelines. While GPT-5.5 holds a clear performance lead, it carries a heavy price premium. Choose GPT-5.5 for complex logic, or DeepSeek V4 Pro for budget efficiency.
WHY?
Benchmark Calculations & Evidence:
  • Coding Benchmarks: Both models were evaluated on the SWE-bench Pro benchmark. GPT-5.5 scored 58.6%, while DeepSeek V4 Pro scored 52.1%.
  • Reasoning Benchmarks: Both models were evaluated on the GPQA Diamond benchmark. GPT-5.5 scored 93.6%, while DeepSeek V4 Pro scored 88%.
  • Cost Efficiency: DeepSeek V4 Pro pricing ($1.74/M input, $3.48/M output) is 5.2x cheaper than GPT-5.5 ($5/M input, $30/M output).
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    Model Specs

    DeepSeek V4 Pro

    Open SourceAPI Available

    Benchmarks & Scores

    Coding (swe-bench-pro)
    52.1%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)
    88%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)5.2x cheaper
    $2.17Input: $1.74 | Output: $3.48
    Context Window
    1.05M tokens
    Model Specs

    GPT-5.5

    Benchmarks & Scores

    Coding (swe-bench-pro)Winner (+6.5%)
    58.6%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)Winner (+5.6%)
    93.6%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)
    $11.25Input: $5.00 | Output: $30.00
    Context WindowLarger
    1.05M tokens

    Frequently Asked Questions about DeepSeek V4 Pro vs GPT-5.5

    DeepSeek V4 Pro is cheaper than GPT-5.5. DeepSeek V4 Pro has a blended cost of $2.17/1M tokens, which is about 5.2x cheaper than GPT-5.5 at $11.25/1M tokens.

    GPT-5.5 is better for coding tasks on this benchmark. It scores 58.6% on swe-bench-pro (complex codebases, multi-file repositories, and architectural planning) compared to DeepSeek V4 Pro which scores 52.1%.

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