AI Model Comparison

Gemini 3.5 Flash vs GPT-5.5

Compare Gemini 3.5 Flash (medium) vs GPT-5.5 (xhigh) with benchmark results, speed, pricing, and practical workflow guidance.

Best For Gemini 3.5 Flash (medium)

  • High-volume, latency-sensitive tasks
  • Cost-effective production workflows
  • Real-time application responses

Best For GPT-5.5 (xhigh)

  • Complex coding and logic projects
  • High-accuracy analytical research
  • Tasks requiring maximum intelligence

Gemini 3.5 Flash offers superior speed and cost-efficiency, while GPT-5.5 provides higher intelligence and coding capabilities. Choosing between them depends on whether your priority is rapid, budget-friendly performance or maximum analytical depth for complex tasks.

Quick Take

Gemini 3.5 Flash (Google) and GPT-5.5 (OpenAI) represent the latest high-performance tiers from their respective organizations. Released in May and April 2026, these models target different operational needs: Gemini 3.5 Flash emphasizes rapid response and affordability, while GPT-5.5 focuses on maximizing intelligence and coding proficiency.

Benchmark Read

GPT-5.5 holds a clear lead in core cognitive benchmarks. It achieves an Intelligence index of 60.2 compared to Gemini 3.5 Flash’s 54.8. This trend continues in coding, where GPT-5.5 scores 59.1 against Gemini’s 43.9.

Specific performance metrics further highlight these differences:

  • GPQA: GPT-5.5 (0.935) vs. Gemini 3.5 Flash (0.921)
  • HLE: GPT-5.5 (0.443) vs. Gemini 3.5 Flash (0.399)
  • SciCode: GPT-5.5 (0.561) vs. Gemini 3.5 Flash (0.53)
  • TerminalBench Hard: GPT-5.5 (0.606) significantly outperforms Gemini 3.5 Flash (0.394).

Gemini 3.5 Flash does show a slight edge in the TAU2 benchmark (0.956 vs 0.939), suggesting specific strengths in agentic or tool-use scenarios.

Cost and Speed

There is a stark contrast in operational efficiency. Gemini 3.5 Flash is significantly more affordable, with a blended cost of $3.38/1M tokens compared to $11.25/1M for GPT-5.5.

Performance speed also favors Gemini:

  • Output Speed: Gemini 3.5 Flash operates at 223.093 tok/s, nearly triple the 84.767 tok/s of GPT-5.5.
  • Latency: Gemini 3.5 Flash offers a time-to-first-token of 13.209s, substantially faster than the 63.085s required by GPT-5.5.

Best Fit

Gemini 3.5 Flash is the optimal choice for high-volume, latency-sensitive applications where cost management is critical. GPT-5.5 is best suited for complex, high-stakes development and analytical tasks where the highest possible intelligence and coding accuracy are required, regardless of the higher price point.

Benchmark table

Side-by-side scores, speed, and pricing for the selected models.

Metric Google Gemini 3.5 Flash (medium) OpenAI GPT-5.5 (xhigh)
Index Scores
Intelligence Index 54.8 60.2
Coding Index 43.9 59.1
Math Index--
Benchmark Scores
GPQA 92.1 93.5
SciCode 53.0 56.1
IFBench 74.6 75.9
HLE 39.9 44.3
LCR 71.0 74.3
TAU2 95.6 93.9
TerminalBench Hard 39.4 60.6

Verdict

Choose Gemini 3.5 Flash if you require high-throughput, cost-effective performance for real-time applications. Its significantly faster time-to-first-token and lower pricing make it ideal for latency-sensitive tasks. Conversely, select GPT-5.5 if your project demands peak intelligence and coding precision, as it consistently outperforms Gemini across primary benchmarks despite the higher cost and slower response times.

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