Quick Take

Gemini 3.5 Flash (released May 19, 2026) and GPT-5.5 (released April 23, 2026) represent the latest advancements from Google and OpenAI. Gemini 3.5 Flash prioritizes high-speed, cost-effective execution, whereas GPT-5.5 focuses on maximizing intelligence and coding proficiency.

Benchmark Read

GPT-5.5 leads in core intelligence metrics, scoring 60.2 on the Intelligence index compared to Gemini 3.5 Flash’s 55.3. This trend continues in coding, where GPT-5.5 achieves a 59.1 index versus 45 for Gemini.

In specific benchmarks, GPT-5.5 outperforms Gemini 3.5 Flash in GPQA (0.935 vs 0.922), HLE (0.443 vs 0.41), SciCode (0.561 vs 0.531), LCR (0.743 vs 0.693), and TerminalBench Hard (0.606 vs 0.409). Gemini 3.5 Flash shows a slight edge in IFBench (0.763 vs 0.758) and a notable lead in TAU2 (0.953 vs 0.938).

Cost and Speed

Gemini 3.5 Flash is significantly more economical, with a blended cost of $3.38/1M tokens compared to $11.25/1M for GPT-5.5. Gemini’s input cost is $1.50/1M and output is $9.00/1M, while GPT-5.5 charges $5.00/1M for input and $30.00/1M for output.

Performance metrics highlight a massive speed disparity. Gemini 3.5 Flash delivers an output speed of 233.027 tok/s with a time to first token of 9.746s. GPT-5.5 is considerably slower, outputting at 60.513 tok/s with a time to first token of 45.731s.

Best Fit

Gemini 3.5 Flash is best suited for high-throughput applications, real-time interactions, and cost-sensitive projects where latency is a critical factor. GPT-5.5 is the optimal choice for complex reasoning, advanced software development, and tasks where the highest possible intelligence index is required, regardless of higher costs and slower response times.