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OpenAIGPT-5.4VSOpenAIGPT-5.5

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

Our Take

We recommend GPT-5.4 for a 2.0x API cost saving at identical performance levels. While both models deliver similar intelligence, GPT-5.4 is the optimal choice for high-volume pipelines. Choose GPT-5.4 for budget efficiency without sacrificing quality.
WHY?
Benchmark Calculations & Evidence:
  • Performance Match: Both models perform almost identically, with an average score gap of just 0.8% across reasoning and coding benchmarks.
  • Coding Benchmarks: Both models were evaluated on the SWE-bench Pro benchmark. GPT-5.4 scored 57.7%, while GPT-5.5 scored 58.6%.
  • Reasoning Benchmarks: Both models were evaluated on the GPQA Diamond benchmark. GPT-5.4 scored 92.8%, while GPT-5.5 scored 93.6%.
  • Cost Efficiency: GPT-5.4 pricing ($2.5/M input, $15/M output) is 2.0x cheaper than GPT-5.5 ($5/M input, $30/M output).
  • Was this recommendation helpful?
    Model Specs

    GPT-5.4

    Benchmarks & Scores

    Coding (swe-bench-pro)
    57.7%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)
    92.8%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)2.0x cheaper
    $5.63Input: $2.50 | Output: $15.00
    Context Window
    1.05M tokens
    Model Specs

    GPT-5.5

    Benchmarks & Scores

    Coding (swe-bench-pro)Winner (+0.9%)
    58.6%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)Winner (+0.8%)
    93.6%

    graduate-level science QA

    Cost & Context

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

    Frequently Asked Questions about GPT-5.4 vs GPT-5.5

    GPT-5.4 is cheaper than GPT-5.5. GPT-5.4 has a blended cost of $5.63/1M tokens, which is about 2.0x 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 GPT-5.4 which scores 57.7%.

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