GoogleGemini 3.5 FlashVSOpenAIGPT-5.5
Our Take
We recommend GPT-5.5 if your workflow requires peak coding capability, or the 3.3x cheaper Gemini 3.5 Flash to optimize your API budget. While both models deliver similar reasoning performance, GPT-5.5 holds a clear lead in coding. Choose GPT-5.5 for complex development tasks, or Gemini 3.5 Flash for cost optimization.
▶WHY?
Benchmark Calculations & Evidence:
Coding Benchmarks: Both models were evaluated on the SWE-bench Pro benchmark. Gemini 3.5 Flash scored 55.1%, while GPT-5.5 scored 58.6%.
Reasoning Benchmarks: Both models were evaluated on the GPQA Diamond benchmark. Gemini 3.5 Flash scored 92.2%, while GPT-5.5 scored 93.6%.
Cost Efficiency: Gemini 3.5 Flash pricing ($1.5/M input, $9/M output) is 3.3x cheaper than GPT-5.5 ($5/M input, $30/M output).
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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)3.3x cheaper
$3.38Input: $1.50 | Output: $9.00Context Window
1.05M tokensBenchmarks & Scores
Coding (swe-bench-pro)Winner (+3.5%)
58.6%complex codebases, multi-file repositories, and architectural planning
Reasoning (gpqa-diamond)Winner (+1.4%)
93.6%graduate-level science QA
Cost & Context
Cost (per 1M tokens)
$11.25Input: $5.00 | Output: $30.00Context WindowLarger
1.05M tokensFrequently Asked Questions about Gemini 3.5 Flash vs GPT-5.5
Gemini 3.5 Flash is cheaper than GPT-5.5. Gemini 3.5 Flash has a blended cost of $3.38/1M tokens, which is about 3.3x 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 Gemini 3.5 Flash which scores 55.1%.
Related Matchups
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