What is the difference between Gemini 3.5 Flash and OpenAI o4-mini?

Gemini 3.5 Flash is developed by Google AI while OpenAI o4-mini is developed by OpenAI. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Gemini 3.5 Flash or OpenAI o4-mini?

It depends on your use case. Gemini 3.5 Flash and OpenAI o4-mini 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 3.5 Flash cost compared to OpenAI o4-mini?

Gemini 3.5 Flash costs $1.5/M input tokens and OpenAI o4-mini costs $1.1/M input tokens. OpenAI o4-mini is $0.40/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 3.5 Flash and OpenAI o4-mini on Rival?

This page shows a side-by-side comparison of Gemini 3.5 Flash and OpenAI o4-mini 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.

What is the difference between Gemini 3.5 Flash and OpenAI o4-mini?

Gemini 3.5 Flash is developed by Google AI while OpenAI o4-mini is developed by OpenAI. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Gemini 3.5 Flash or OpenAI o4-mini?

It depends on your use case. Gemini 3.5 Flash and OpenAI o4-mini 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 3.5 Flash cost compared to OpenAI o4-mini?

Gemini 3.5 Flash costs $1.5/M input tokens and OpenAI o4-mini costs $1.1/M input tokens. OpenAI o4-mini is $0.40/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 3.5 Flash and OpenAI o4-mini on Rival?

This page shows a side-by-side comparison of Gemini 3.5 Flash and OpenAI o4-mini 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.

Gemini 3.5 Flash vs OpenAI o4-mini: Which Is Better?

Updated May 2026

Our Verdict

Gemini 3.5 Flash

OpenAI o4-miniRunner-up

No community votes yet. On paper, Gemini 3.5 Flash has the edge — bigger model tier, newer, bigger context window.

Too close to call

API pricing

Cost per 1M tokens

Gemini 3.5 Flash

Input

$1.50

Output

$9.00

OpenAI o4-mini

Input

$1.10

1.4× cheaper

Output

$4.40

2.0× cheaper

OpenAI o4-mini is cheaper on both — 1.4× input, 2.0× output

Writing DNA

Style Comparison

Similarity

55%

Gemini 3.5 Flash uses 442.3x more bold

Gemini 3.5 Flash

OpenAI o4-mini

59%Vocabulary73%

18wSentence Length15w

0.16Hedging0.18

4.4Bold0.0

3.0Lists2.1

0.00Emoji0.00

0.89Headings0.00

0.11Transitions0.02

Based on 27 + 10 text responses

Research

What we learned reading every model

Gemini 3.5 Flash and OpenAI o4-mini have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

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OpenAI o4-mini vs Claude Sonnet 4New provider

OpenAI o4-mini vs Llama 4 MaverickNew provider

Updated May 2026

Our Verdict

Gemini 3.5 Flash

OpenAI o4-miniRunner-up

No community votes yet. On paper, Gemini 3.5 Flash has the edge — bigger model tier, newer, bigger context window.

Too close to call

API pricing

Cost per 1M tokens

Gemini 3.5 Flash

Input

$1.50

Output

$9.00

OpenAI o4-mini

Input

$1.10

1.4× cheaper

Output

$4.40

2.0× cheaper

OpenAI o4-mini is cheaper on both — 1.4× input, 2.0× output

Writing DNA

Style Comparison

Similarity

55%

Gemini 3.5 Flash uses 442.3x more bold

Gemini 3.5 Flash

OpenAI o4-mini

59%Vocabulary73%

18wSentence Length15w

0.16Hedging0.18

4.4Bold0.0

3.0Lists2.1

0.00Emoji0.00

0.89Headings0.00

0.11Transitions0.02

Based on 27 + 10 text responses

Research

What we learned reading every model

Gemini 3.5 Flash and OpenAI o4-mini have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

OpenAI o4-mini vs MiniMax M3New provider

OpenAI o4-mini vs Claude Sonnet 4New provider

OpenAI o4-mini vs Llama 4 MaverickNew provider