GoogleGemini 3.5 FlashVSOpenAIGPT-5.6 Terra

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

Our Take

If your budget allows, GPT-5.6 Terra is the superior choice here, offering a clear benchmark advantage while carrying only a moderate price premium (1.7x). We recommend choosing Gemini 3.5 Flash only if you need to optimize costs for very high-volume pipelines.

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Model Specs

Gemini 3.5 Flash

Website

Benchmarks & Scores

Coding (swe-bench-pro)

55.1%

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

Reasoning (gpqa-diamond)

92.2%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)1.7x cheaper

$3.38Input: $1.50 | Output: $9.00

Context Window

1.05M tokens

Model Specs

GPT-5.6 Terra

Website

Benchmarks & Scores

Coding (swe-bench-pro)Winner (+8.3%)

63.4%

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

Reasoning (gpqa-diamond)Winner (+0.7%)

92.9%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)

$5.63Input: $2.50 | Output: $15.00

Context WindowLarger

1.05M tokens

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Frequently Asked Questions about Gemini 3.5 Flash vs GPT-5.6 Terra

Gemini 3.5 Flash is cheaper than GPT-5.6 Terra. Gemini 3.5 Flash has a blended cost of $3.38/1M tokens, which is about 1.7x cheaper than GPT-5.6 Terra at $5.63/1M tokens.

GPT-5.6 Terra is better for coding tasks on this benchmark. It scores 63.4% on swe-bench-pro (excellent at multi-file repositories, autonomous agents, and industrial codebases) compared to Gemini 3.5 Flash which scores 55.1%.

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