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  5. Gemini 2.5 Flash Preview 05-20 (thinking)vsGPT-6 Luna Pro
Updated Sep 2026

Gemini 2.5 Flash Preview 05-20 (thinking)vsGPT-6 Luna Pro

GPT-6 Luna Pro is cheaper than Gemini 2.5 Flash Preview 05-20 (thinking) at $0.1/M vs $0.15/M input tokens.

Gemini 2.5 Flash Preview 05-20 (thinking) and GPT-6 Luna Pro compared across 1 shared prompts
SpecGemini 2.5 Flash Preview 05-20 (thinking)GPT-6 Luna Pro
Input price$0.15/M tokens$0.1/M tokens
Output price$3.5/M tokens$0.5/M tokens
Context window1.0M tokens1.1M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedMay 2025Sep 2026
Our Verdict
GPT-6 Luna Pro
GPT-6 Luna Pro
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, GPT-6 Luna Pro has the edge: bigger model tier, newer.

GPT-6 Luna Pro costs 7.0x 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 (thinking)
Input
$0.15
Output
$3.50
GPT-6 Luna Pro
Input
$0.10
1.5× cheaper
Output
$0.50
7.0× cheaper

GPT-6 Luna Pro is cheaper on both: 1.5× input, 7.0× output.

Where to run it

2 hosts

Gemini 2.5 Flash Preview 05-20 (thinking)

No hosts listed on OpenRouter.

GPT-6 Luna Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·98.6% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Gemini 2.5 Flash Preview 05-20 (thinking) is developed by Google AI while GPT-6 Luna Pro is developed by OpenAI. Gemini 2.5 Flash Preview 05-20 (thinking) has a 1.0M token context window vs GPT-6 Luna Pro's 1.1M. You can compare their actual outputs across 1 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 GPT-6 Luna Pro each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 1 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 GPT-6 Luna Pro costs $0.1/M input tokens. GPT-6 Luna Pro is $0.05/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 GPT-6 Luna 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.

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Model pages

Gemini 2.5 Flash Preview 05-20 (thinking) logo
Gemini 2.5 Flash Preview 05-20 (thinking)12 outputs, specs and price
GPT-6 Luna Pro logo
GPT-6 Luna Pro20 outputs, specs and price
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