What is the difference between Gemini 3.5 Flash and GPT-6 Astra Pro?

Gemini 3.5 Flash is developed by Google AI while GPT-6 Astra Pro is developed by OpenAI. Gemini 3.5 Flash has a 1.0M token context window vs GPT-6 Astra Pro's 1.1M. You can compare their actual outputs across 6 challenges on Rival to see how they differ in practice.

Which is better, Gemini 3.5 Flash or GPT-6 Astra Pro?

It depends on your use case. Gemini 3.5 Flash and GPT-6 Astra Pro each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 6 challenges so you can judge which fits your needs best.

How much does Gemini 3.5 Flash cost compared to GPT-6 Astra Pro?

Gemini 3.5 Flash costs $1.5/M input tokens and GPT-6 Astra Pro costs $10/M input tokens. Gemini 3.5 Flash is $8.50/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 GPT-6 Astra Pro on Rival?

This page shows a side-by-side comparison of Gemini 3.5 Flash and GPT-6 Astra Pro 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 3.5 FlashvsGPT-6 Astra Pro

Gemini 3.5 Flash is cheaper than GPT-6 Astra Pro at $1.5/M vs $10/M input tokens.

Gemini 3.5 Flash and GPT-6 Astra Pro compared across 6 shared prompts
Spec	Gemini 3.5 Flash	GPT-6 Astra Pro
Input price	$1.5/M tokens	$10/M tokens
Output price	$9/M tokens	$50/M tokens
Context window	1.0M tokens	1.1M tokens
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	May 2026	Sep 2026

Our Verdict

GPT-6 Astra Pro

Gemini 3.5 FlashRunner-up

Not enough votes to call it. On the specs, GPT-6 Astra Pro has the edge: bigger model tier, newer.

Gemini 3.5 Flash costs 5.6x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 3.5 Flash

Input

$1.50

6.7× cheaper

Output

$9.00

5.6× cheaper

GPT-6 Astra Pro

Input

$10.00

Output

$50.00

Gemini 3.5 Flash is cheaper on both: 6.7× input, 5.6× output.

Where to run it

4 hosts, cheapest first

Gemini 3.5 Flash2 hosts

HostInOutContextUptime

Google Vertex AI$0.75 in$4.50 out1M76% up Google AI Studio$1.50 in$9.00 out1M99.9% up

GPT-6 Astra Pro2 hosts

HostInOutContextUptime

Azure AI Foundry$10.00 in$50.00 out1.1M98.9% up OpenAI$10.00 in$50.00 out1.1M99.6% up

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

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Cost per 1M tokens

4 hosts, cheapest first

What we learned reading every model

Common questions

What is the difference between Gemini 3.5 Flash and GPT-6 Astra Pro?

Which is better, Gemini 3.5 Flash or GPT-6 Astra Pro?

How much does Gemini 3.5 Flash cost compared to GPT-6 Astra Pro?

How can I compare Gemini 3.5 Flash and GPT-6 Astra Pro on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages

Cost per 1M tokens

4 hosts, cheapest first

What we learned reading every model

Common questions

What is the difference between Gemini 3.5 Flash and GPT-6 Astra Pro?

Which is better, Gemini 3.5 Flash or GPT-6 Astra Pro?

How much does Gemini 3.5 Flash cost compared to GPT-6 Astra Pro?

How can I compare Gemini 3.5 Flash and GPT-6 Astra Pro on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages