GoogleGemini 2.5 Flash-LiteVSGoogleGemini 3.1 Pro

Analysis by:the whichllmmodel Editorial Team|Updated: June 2026

Our Take

We recommend Gemini 3.1 Pro if you need peak intelligence for complex complex codebases, multi-file repositories, and architectural planning, or the 25.7x cheaper Gemini 2.5 Flash-Lite if your workflow is limited to multi-file code and clearly defined tasks. While Gemini 3.1 Pro holds a major reasoning advantage, Gemini 2.5 Flash-Lite is optimized for high-volume budget pipelines. Choose Gemini 3.1 Pro for architectural codebase planning, or Gemini 2.5 Flash-Lite to maximize your budget for basic scripts.

▶WHY?

Benchmark Calculations & Evidence:

Coding Evaluation: Gemini 2.5 Flash-Lite was evaluated on SWE-bench Verified (scoring 41.3%), while Gemini 3.1 Pro was evaluated on SWE-bench Pro (scoring 54.2%).

Reasoning Accuracy: Both models were evaluated on the GPQA Diamond benchmark. Gemini 3.1 Pro scored 94.3%, while Gemini 2.5 Flash-Lite scored 62.5%.

Cost Efficiency: Gemini 2.5 Flash-Lite pricing ($0.1/M input, $0.4/M output) is 25.7x cheaper than Gemini 3.1 Pro ($2/M input, $12/M output).

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Model Specs

Gemini 2.5 Flash-Lite

Website

Benchmarks & Scores

Coding (swe-bench-verified)

41.3%

multi-file code and clearly defined tasks

Reasoning (gpqa-diamond)

62.5%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)25.7x cheaper

$0.17Input: $0.10 | Output: $0.40

Context Window

1.05M tokens

Model Specs

Gemini 3.1 Pro

Website

Benchmarks & Scores

Coding (swe-bench-pro)

54.2%

complex codebases, multi-file repositories, and architectural planning

Reasoning (gpqa-diamond)Winner (+31.8%)

94.3%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)

$4.50Input: $2.00 | Output: $12.00

Context Window

1.05M tokens

Read our data collection methodology

Frequently Asked Questions about Gemini 2.5 Flash-Lite vs Gemini 3.1 Pro

Gemini 2.5 Flash-Lite is cheaper than Gemini 3.1 Pro. Gemini 2.5 Flash-Lite has a blended cost of $0.17/1M tokens, which is about 25.7x cheaper than Gemini 3.1 Pro at $4.50/1M tokens.

For coding tasks, Gemini 2.5 Flash-Lite scores 41.3% on swe-bench-verified (multi-file code and clearly defined tasks), while Gemini 3.1 Pro scores 54.2% on swe-bench-pro (complex codebases, multi-file repositories, and architectural planning).

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