Gemini 3.1 Pro vs Gemini 3.5 Flash
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
Gemini 3.5 Flash by Google wins on 8 of 11 benchmarks against Gemini 3.1 Pro by Google, which leads on 2. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
General Intelligence: In general intelligence, Gemini 3.5 Flash scores 33 on AA Intelligence Index compared to Gemini 3.1 Pro's 30.4.
Coding: In coding, Gemini 3.5 Flash scores 70.1 on AA Coding Index compared to Gemini 3.1 Pro's 68.8, while Gemini 3.5 Flash scores 1275 on Design Arena ELO compared to Gemini 3.1 Pro's 1256, while Gemini 3.5 Flash scores 1275 on Website Arena ELO compared to Gemini 3.1 Pro's 1246.
Reasoning: In reasoning, Gemini 3.1 Pro scores 94.4% on GPQA Diamond compared to Gemini 3.5 Flash's 92.8%, while Gemini 3.5 Flash scores 27.3 on AA Agentic Index compared to Gemini 3.1 Pro's 10.3, while Gemini 3.1 Pro scores 75.3% on τ²-Bench Airline compared to Gemini 3.5 Flash's 74.7%.
Context: In context, both score 1.0M on Context Length.
Pricing Comparison
Gemini 3.1 Pro costs $2.0/1M input tokens and $12.0/1M output tokens, while Gemini 3.5 Flash costs $1.5/1M input and $9.0/1M output. Gemini 3.5 Flash is the more affordable option for API usage.
Verdict
Gemini 3.5 Flash leads across the board in affordability, making it the stronger overall choice in this comparison.
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Gemini 3.1 Pro vs Gemini 3.5 Flash — FAQ
Which is better, Gemini 3.1 Pro or Gemini 3.5 Flash?
Gemini 3.5 Flash wins on more benchmarks overall (8 vs 2). However, the best choice depends on your specific needs — each model excels in different areas.
How does Gemini 3.1 Pro compare to Gemini 3.5 Flash for coding?
SWE-bench Verified data is not available for both models. Check the detailed comparison charts above for other coding-related metrics.
Is Gemini 3.1 Pro cheaper than Gemini 3.5 Flash?
Yes, Gemini 3.5 Flash is cheaper. Gemini 3.1 Pro costs $2.0/1M input and $12.0/1M output tokens. Gemini 3.5 Flash costs $1.5/1M input and $9.0/1M output tokens.
Which is faster, Gemini 3.1 Pro or Gemini 3.5 Flash?
Output speed data is not available for both models. Check the speed section of the comparison above for available performance data.
What benchmarks does the Gemini 3.1 Pro vs Gemini 3.5 Flash comparison cover?
This comparison covers 11 benchmarks including GPQA Diamond, Input Cost, Output Cost, Context Length, AA Intelligence Index, AA Coding Index, AA Agentic Index, Cached Input Cost, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.