GoogleGemini 2.5 FlashVSOpenAIGPT-5.6 Terra

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

Our Take

These models use different coding evaluation benchmarks — with Gemini 2.5 Flash evaluated on swe-bench-verified (good at editing existing code, cross-file updates, and multi-component systems) and GPT-5.6 Terra on swe-bench-pro (excellent at multi-file repositories, autonomous agents, and industrial codebases) — but GPT-5.6 Terra holds a clear reasoning advantage (+24.6% on GPQA Diamond). However, Gemini 2.5 Flash is a massive 6.6x cheaper to run. Choose GPT-5.6 Terra for complex logic and reasoning tasks, or Gemini 2.5 Flash to optimize your budget for high-volume pipelines.

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Model Specs

Gemini 2.5 Flash

Website

Benchmarks & Scores

Coding (swe-bench-verified)

60.4%

good at editing existing code, cross-file updates, and multi-component systems

Reasoning (gpqa-diamond)

68.3%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)6.6x cheaper

$0.85Input: $0.30 | Output: $2.50

Context Window

1.05M tokens

Model Specs

GPT-5.6 Terra

Website

Benchmarks & Scores

Coding (swe-bench-pro)

63.4%

excellent at multi-file repositories, autonomous agents, and industrial codebases

Reasoning (gpqa-diamond)Winner (+24.6%)

92.9%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)

$5.63Input: $2.50 | Output: $15.00

Context WindowLarger

1.05M tokens

Read our data collection methodology

Frequently Asked Questions about Gemini 2.5 Flash vs GPT-5.6 Terra

Gemini 2.5 Flash is cheaper than GPT-5.6 Terra. Gemini 2.5 Flash has a blended cost of $0.85/1M tokens, which is about 6.6x cheaper than GPT-5.6 Terra at $5.63/1M tokens.

For coding tasks, Gemini 2.5 Flash scores 60.4% on swe-bench-verified (good at editing existing code, cross-file updates, and multi-component systems), while GPT-5.6 Terra scores 63.4% on swe-bench-pro (excellent at multi-file repositories, autonomous agents, and industrial codebases).

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