Which model is better: Gemini 2.5 Flash or Gemini 3.1 Pro?
Gemini 2.5 Flash is 76.0% cheaper for input tokens ($0.30 vs. $1.25 per 1M tokens) and $2.50 vs. $10.00 for output tokens (4.2x cost advantage). In terms of operational performance, Gemini 2.5 Flash delivers lower response latency at 110ms TTFT (310ms faster than Gemini 3.1 Pro) with 180 vs. 98 tok/s throughput. Gemini 3.1 Pro leads coding evaluations at 71.8% SWE-bench Verified vs. 58.0% for Gemini 2.5 Flash and 82.4% vs. 70.5% on GPQA Diamond.
Verified daily via automated API latency tests and official documentation.
Zero-Shot RAG Verified
Verified Performance & Unit Economics Delta (12 Dimensions)
Daily synchronized metrics across token pricing, prompt cache economics, latency, throughput, and 5 capability benchmarks.
Metric / Dimension
Gemini 2.5 Flash
Gemini 3.1 Pro
Net Delta / Advantage
Input Cost / 1M Tokens
$0.30
$1.25
Gemini 2.5 Flash is 4.2x cheaper
Output Cost / 1M Tokens
$2.50
$10.00
Gemini 2.5 Flash (75.0% lower)
Prompt Cache Read / 1M
$0.030
$0.310
Gemini 2.5 Flash is 10.3x cheaper
Prompt Cache Write / 1M
$0.30
$1.25
Gemini 2.5 Flash is 4.2x cheaper
Context Window (Max Output)
1,049k (66k out)
1,049k (66k out)
Equal Context Window
Avg TTFT Response Latency
110ms
420ms
Gemini 2.5 Flash (310ms faster)
Generation Speed (Throughput)
180 tok/s
98 tok/s
Gemini 2.5 Flash (+82 tok/s faster)
SWE-bench Verified (Coding)
58%
71.8%
Gemini 3.1 Pro (+13.8% lead)
GPQA Diamond (PhD STEM)
70.5%
82.4%
Gemini 3.1 Pro (+11.9% lead)
MMLU-Pro (Multi-Discipline)
82%
89.5%
Gemini 3.1 Pro (+7.5% lead)
MATH-500 (Quantitative Logic)
89%
96.8%
Gemini 3.1 Pro (+7.8% lead)
Inference Value Score (IVR)
66.6 / 100
60 / 100
Gemini 2.5 Flash (+6.6 pts)
Interactive Monthly Token Economics & ROI Forecaster
Model production workloads across prompt, completion, and cached context tokens, or switch models on the fly.
Choose Gemini 3.1 Pro (Google) for complex enterprise architecture planning, multi-file code refactoring, legal/financial corpus auditing, and multimodal research — offering a 1,048k context window, 420ms TTFT, and $1.25/1M input pricing ($0.310/1M cached reads).
Which is cheaper: Gemini 2.5 Flash or Gemini 3.1 Pro?
Gemini 2.5 Flash is cheaper at $0.30/1M input tokens ($2.50/1M output) compared to $1.25/1M input ($10.00/1M output) for Gemini 3.1 Pro.
Which model has lower TTFT latency and higher tok/s throughput: Gemini 2.5 Flash or Gemini 3.1 Pro?
Gemini 2.5 Flash delivers faster first-token latency at 110ms TTFT (180 tok/s throughput) compared to 420ms TTFT (98 tok/s) for Gemini 3.1 Pro.
How do Gemini 2.5 Flash and Gemini 3.1 Pro compare on SWE-bench coding and GPQA Diamond reasoning?
On SWE-bench Verified software engineering, Gemini 2.5 Flash scores 58% versus 71.8% for Gemini 3.1 Pro. On GPQA Diamond graduate-level STEM reasoning, Gemini 2.5 Flash scores 70.5% versus 82.4% for Gemini 3.1 Pro (and 89% vs 96.8% on MATH-500).
When should you choose Gemini 2.5 Flash?
Choose Gemini 2.5 Flash (Google) for cost-efficient 1M-context summarization, multimodal extraction, and interactive assistants — offering a 1,048k context window, 110ms TTFT, and $0.30/1M input pricing ($0.030/1M cached reads).
When should you choose Gemini 3.1 Pro?
Choose Gemini 3.1 Pro (Google) for complex enterprise architecture planning, multi-file code refactoring, legal/financial corpus auditing, and multimodal research — offering a 1,048k context window, 420ms TTFT, and $1.25/1M input pricing ($0.310/1M cached reads).
