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  5. Gemini 2.5 Flash Preview 05-20 (thinking)vsGemini 3.5 Flash
Updated May 2026

Gemini 2.5 Flash Preview 05-20 (thinking)vsGemini 3.5 Flash

Gemini 2.5 Flash Preview 05-20 (thinking) is cheaper than Gemini 3.5 Flash at $0.15/M vs $1.5/M input tokens.

Gemini 2.5 Flash Preview 05-20 (thinking) and Gemini 3.5 Flash compared across 11 shared prompts
SpecGemini 2.5 Flash Preview 05-20 (thinking)Gemini 3.5 Flash
Input price$0.15/M tokens$1.5/M tokens
Output price$3.5/M tokens$9/M tokens
Context window1.0M tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedMay 2025May 2026
Side by side

Same prompt, both answers

Opening lines from 2 of the 11 prompts both answered. Formatting stripped, words untouched.

Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

Gemini 2.5 Flash Preview 05-20 (thinking)467 words
(Lights up on a stage. Comedian walks to center, adjusts mic, smiles warmly.) \"Alright, alright, settle down you crazy people! Thanks for having me. (Pause fo r applause/laughter) You know, I was scrolling through Instagram earlier, and it\'s just a constant ba rrage of people \'living thei r best life,\' isn\'t it?
Read the full answer
Gemini 3.5 Flash557 words
[The comedian walks onto the stage, adjusts the mic stand, and smiles at the crowd.] How’s everyone doing tonight? (Wait for response) Good, good. I’m doing okay, but I recently crossed a major threshold in my life. I hit the age where my body has started making its own decisions without consulting me first.
Read the full answer

Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Gemini 2.5 Flash Preview 05-20 (thinking)93 words
Here are 5 jokes: Why don\'t scientists trust atoms? Because they make up everything! What do you call a fake noodle? An impasta! Why did the scarecrow win an award? Because he was outstanding in his field! I told my wife she was drawing her eyebrows too high. She looked surprised.
Read the full answer
Gemini 3.5 Flash83 words
Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! What do you call a fake noodle? An impasta! Why did the scarecrow win an award? Because he was outstanding in his field! How do you organize a space party? You planet. Why don't skeletons fight each other? They don't have the guts.
Read the full answer
Our Verdict
Gemini 3.5 Flash
Gemini 3.5 Flash
Gemini 2.5 Flash Preview 05-20 (thinking)
Gemini 2.5 Flash Preview 05-20 (thinking)Runner-up

Not enough votes to call it. On the specs, Gemini 3.5 Flash has the edge: bigger model tier, newer.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 2.5 Flash Preview 05-20 (thinking)
Input
$0.15
10× cheaper
Output
$3.50
2.6× cheaper
Gemini 3.5 Flash
Input
$1.50
Output
$9.00

Gemini 2.5 Flash Preview 05-20 (thinking) is cheaper on both: 10× input, 2.6× output.

Where to run it

2 hosts, cheapest first

Gemini 2.5 Flash Preview 05-20 (thinking)

No hosts listed on OpenRouter.

Gemini 3.5 Flash2 hosts
HostInOutContextUptime
Google Vertex AI$0.75 in·$4.50 out·1M·69.5% upGoogle AI Studio$1.50 in·$9.00 out·1M·99.8% up

Per million tokens. Prices and uptime via OpenRouter, checked 23 Sep 2026.

Writing DNA

Style Comparison

Similarity
54%

Gemini 3.5 Flash uses 15.7x more hedging

Gemini 2.5 Flash Preview 05-20 (thinking)
Gemini 3.5 Flash
70%Vocabulary59%
11wSentence Length18w
0.00Hedging0.16
4.2Bold4.4
7.3Lists3.0
0.00Emoji0.00
0.00Headings0.89
0.00Transitions0.11
Based on 3 + 27 text responses
Research

What we learned reading every model

FAQ

Common questions

Both are developed by Google AI but target different use cases. Gemini 2.5 Flash Preview 05-20 (thinking) has a 1.0M token context window vs Gemini 3.5 Flash's 1.0M. You can compare their actual outputs across 11 challenges on Rival to see how they differ in practice.

It depends on your use case. Gemini 2.5 Flash Preview 05-20 (thinking) and Gemini 3.5 Flash each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 11 challenges so you can judge which fits your needs best.

Gemini 2.5 Flash Preview 05-20 (thinking) costs $0.15/M input tokens and Gemini 3.5 Flash costs $1.5/M input tokens. Gemini 2.5 Flash Preview 05-20 (thinking) is $1.35/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Gemini 2.5 Flash Preview 05-20 (thinking) and Gemini 3.5 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.

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Model pages

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Gemini 3.5 Flash58 outputs, specs and price
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