What is the difference between Gemini 3.1 Pro Preview and Gemini 3.8 Flash?

Both are developed by Google AI but target different use cases. Gemini 3.1 Pro Preview has a 1.0M token context window vs Gemini 3.8 Flash's 1.0M. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Gemini 3.1 Pro Preview or Gemini 3.8 Flash?

It depends on your use case. Gemini 3.1 Pro Preview and Gemini 3.8 Flash each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does Gemini 3.1 Pro Preview cost compared to Gemini 3.8 Flash?

Gemini 3.1 Pro Preview costs $2/M input tokens and Gemini 3.8 Flash costs $0.75/M input tokens. Gemini 3.8 Flash is $1.25/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Gemini 3.1 Pro Preview and Gemini 3.8 Flash on Rival?

This page shows a side-by-side comparison of Gemini 3.1 Pro Preview and Gemini 3.8 Flash across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

Updated Sep 2026

Gemini 3.1 Pro PreviewvsGemini 3.8 Flash

Gemini 3.8 Flash is cheaper than Gemini 3.1 Pro Preview at $0.75/M vs $2/M input tokens.

Gemini 3.1 Pro Preview and Gemini 3.8 Flash compared across 53 shared prompts
Spec	Gemini 3.1 Pro Preview	Gemini 3.8 Flash
Input price	$2/M tokens	$0.75/M tokens
Output price	$12/M tokens	$3.75/M tokens
Context window	1.0M tokens	1.0M tokens
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	Feb 2026	Sep 2026