What is the difference between Gemini 2.5 Flash Preview 05-20 and Gemini 3.8 Flash?

Both are developed by Google AI but target different use cases. Gemini 2.5 Flash Preview 05-20 has a 1.0M token context window vs Gemini 3.8 Flash's 1.0M. You can compare their actual outputs across 11 challenges on Rival to see how they differ in practice.

Which is better, Gemini 2.5 Flash Preview 05-20 or Gemini 3.8 Flash?

It depends on your use case. Gemini 2.5 Flash Preview 05-20 and Gemini 3.8 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.

How much does Gemini 2.5 Flash Preview 05-20 cost compared to Gemini 3.8 Flash?

Gemini 2.5 Flash Preview 05-20 costs $0.15/M input tokens and Gemini 3.8 Flash costs $0.75/M input tokens. Gemini 2.5 Flash Preview 05-20 is $0.60/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 2.5 Flash Preview 05-20 and Gemini 3.8 Flash on Rival?

This page shows a side-by-side comparison of Gemini 2.5 Flash Preview 05-20 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 2.5 Flash Preview 05-20vsGemini 3.8 Flash

Gemini 2.5 Flash Preview 05-20 is cheaper than Gemini 3.8 Flash at $0.15/M vs $0.75/M input tokens.

Gemini 2.5 Flash Preview 05-20 and Gemini 3.8 Flash compared across 11 shared prompts
Spec	Gemini 2.5 Flash Preview 05-20	Gemini 3.8 Flash
Input price	$0.15/M tokens	$0.75/M tokens
Output price	$0.6/M tokens	$3.75/M tokens
Context window	1.0M tokens	1.0M tokens
Weights	—	Closed
Free API (OpenRouter)	No	No
Released	May 2025	Sep 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 05-20569 words

Alright, alright, settle down you magnificent collection of human beings! You look good tonight. Not just good, but… like you've all collectively decided to nail the 'I'm here to laugh and avoid talking about my Monday' look. And I respect that. Seriously though, it's great to be back on stage. I'm living the dream.

Read the full answer

Gemini 3.8 Flash502 words

Title: The Quantified Idiot Estimated Time: ~3 minutes (approx. 400–450 words with pauses for delivery) [Walk to center mic. Take it off the stand, leave the stand behind you.] I recently bought a smartwatch because I decided I wasn’t feeling inadequate often enough throughout the day.

Read the full answer

Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Gemini 2.5 Flash Preview 05-2079 words

Here are 5 jokes for you: 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 3.8 Flash76 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! Why couldn't the bicycle stand up by itself? It was two tired!

Read the full answer

Our Verdict

Gemini 3.8 Flash

Gemini 2.5 Flash Preview 05-20Runner-up

Not enough votes to call it. On the specs, Gemini 3.8 Flash has the edge: bigger model tier, newer.

Gemini 2.5 Flash Preview 05-20 costs 6.3x less per token.

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

Input

$0.15

5.0× cheaper

Output

$0.60

6.3× cheaper

Gemini 3.8 Flash

Input

$0.75

Output

$3.75

Gemini 2.5 Flash Preview 05-20 is cheaper on both: 5.0× input, 6.3× output.

Where to run it

2 hosts, cheapest first

Gemini 2.5 Flash Preview 05-20

No hosts listed on OpenRouter.

Gemini 3.8 Flash2 hosts

HostInOutContextUptime

Google Vertex AI$0.38 in$1.88 out1M82.1% up Google AI Studio$0.75 in$3.75 out1M99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

Writing DNA

Style Comparison

Similarity

57%

Gemini 2.5 Flash Preview 05-20

Gemini 3.8 Flash

69%Vocabulary63%

10wSentence Length20w

0.26Hedging0.17

1.1Bold4.0

5.5Lists2.4

0.00Emoji0.01

0.00Headings0.84

0.00Transitions0.06

Based on 2 + 27 text responses

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Same prompt, both answers

Generate a Stand-Up Routine

Stochastic Consistency Test

Cost per 1M tokens

2 hosts, cheapest first

Style Comparison

What we learned reading every model

Common questions

What is the difference between Gemini 2.5 Flash Preview 05-20 and Gemini 3.8 Flash?

Which is better, Gemini 2.5 Flash Preview 05-20 or Gemini 3.8 Flash?

How much does Gemini 2.5 Flash Preview 05-20 cost compared to Gemini 3.8 Flash?

How can I compare Gemini 2.5 Flash Preview 05-20 and Gemini 3.8 Flash on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages

Same prompt, both answers

Generate a Stand-Up Routine

Stochastic Consistency Test

Cost per 1M tokens

2 hosts, cheapest first

Style Comparison

What we learned reading every model

Common questions

What is the difference between Gemini 2.5 Flash Preview 05-20 and Gemini 3.8 Flash?

Which is better, Gemini 2.5 Flash Preview 05-20 or Gemini 3.8 Flash?

How much does Gemini 2.5 Flash Preview 05-20 cost compared to Gemini 3.8 Flash?

How can I compare Gemini 2.5 Flash Preview 05-20 and Gemini 3.8 Flash on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages