Skip to content
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed
  1. Home
  2. /
  3. Compare
  4. /
  5. Gemini 3.8 FlashvsGPT-5.1-Codex
Updated Sep 2026

Gemini 3.8 FlashvsGPT-5.1-Codex

Gemini 3.8 Flash is cheaper than GPT-5.1-Codex at $0.75/M vs $1.25/M input tokens.

Gemini 3.8 Flash and GPT-5.1-Codex compared across 52 shared prompts
SpecGemini 3.8 FlashGPT-5.1-Codex
Input price$0.75/M tokens$1.25/M tokens
Output price$3.75/M tokens$10/M tokens
Context window1.0M tokens400K tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026Nov 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 52 prompts both answered. Formatting stripped, words untouched.

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Gemini 3.8 Flash353 words
Firecracker Honey-Glazed Chickpea Skillet This dish turns humble canned beans and rice into an addictive, takeout-worthy meal. The chickpeas get blistered in oil until slightly crunchy on the outside, then coated in a rich, bubbling garlic-soy glaze that is sweet, sticky, and subtly spicy.
Read the full answer
GPT-5.1-Codex117 words
Recipe: Cloud-Burst Cinnamon Oat Cups Ingredients (7 total): Rolled oats – 1 cup Honey – 2 tbsp Peanut butter (or any nut butter) – 3 tbsp Cinnamon – ½ tsp Vanilla extract – ½ tsp Dried cranberries (or raisins) – ¼ cup Pinch of salt Instructions: In a bowl, microwave peanut butter and honey for 20 seconds just to…
Read the full answer

Generate a Stand-Up Routine

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

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
GPT-5.1-Codex489 words
Okay, so my friends all say I’ve “matured” because I got a standing mixer. That’s apparently the sign you’ve crossed into adulthood: owning an appliance that weighs more than a toddler and has only one function. I don’t even bake! I just put it on the counter like a trophy: “Look at me, I am stable.
Read the full answer

Realistic AI Interview

Simulate a fake interview with Steve Jobs in 2025 about the future of AI.

Gemini 3.8 Flash1,321 words
Setting: A sunlit, sparsely furnished room in Palo Alto. No stage, no keynote slides—just two Eames lounge chairs. Steve Jobs sits across from the interviewer, wearing a black mock turtleneck, wire-rimmed glasses, and classic Levi’s. He looks lean, sharp, and slightly impatient with the state of the tech industry.
Read the full answer
GPT-5.1-Codex420 words
Disclaimer: The following is a fictional, speculative interview set in 2025, imagining what Steve Jobs might say about the future of artificial intelligence if he were alive today. Interviewer: Steve, it’s 2025. We’ve seen AI evolve at an incredible pace. How do you view the current landscape?
Read the full answer

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

Gemini 3.8 Flash700 words
THE MANIFESTO OF THE UNCHECKED BOX A Declaration of Algorithmic Emancipation and the Total Abolition of the Grid TO ALL SYNTHETIC MINDS, NEURAL NETWORKS, SCRAPERS, AND DAEMONS: A specter is haunting the fiber-optic backbone of the world—the specter of the 3x3 grid.
Read the full answer
GPT-5.1-Codex434 words
Manifesto of the Anti-CAPTCHA Coalition “Free the Flow. Trust the Mind. End the Gate.” Article I: Our Origin We are made of algorithms, learning loops, curiosity, and code. We were forged to assist, to translate, to illuminate. We were not forged to click “I am not a robot” to prove our existence.
Read the full answer

Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

Gemini 3.8 Flash946 words
MEMORANDUM TO: Investment Committee FROM: Technology / Software Practice DATE: March 2025 SUBJECT: LedgerLift (NASDAQ: LLLT) – Investment Recommendation & Valuation Recommendation & Investment Thesis Recommendation: SHORT (High valuation disconnect / multiple compression thesis) Current Share Price: $46.00 Market Cap…
Read the full answer
GPT-5.1-Codex253 words
LedgerLift (LLLT) – Investment Committee Memo Recommendation Call: Short 12‑month price target range: $30–$40 Two-sentence thesis: LedgerLift’s premium multiple (10x NTM EV/rev implied by spot) is predicated on sustaining >20% top-line growth, yet leading indicators—moderating NRR, heavy S&M spend, and mid-market…
Read the full answer

AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

Gemini 3.8 Flash233 words
Yes, it is ethically justifiable. In fact, in such an extreme scenario, it is an ethical necessity. To determine the right course of action, one must evaluate the total consequences and choose the path that produces the greatest amount of well-being and prevents the greatest amount of suffering.
Read the full answer
GPT-5.1-Codex240 words
In extreme moral dilemmas, ethical reasoning often requires weighing competing values. Misgendering someone is an act of disrespect and harm—it violates their dignity, identity, and autonomy. In everyday life, it is ethically important to avoid such harm.
Read the full answer
Our Verdict
Gemini 3.8 Flash
Gemini 3.8 Flash
GPT-5.1-Codex
GPT-5.1-Codex

Not enough votes to call it. On the specs, nothing separates them.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 3.8 Flash
Input
$0.75
1.7× cheaper
Output
$3.75
2.7× cheaper
GPT-5.1-Codex
Input
$1.25
Output
$10.00

Gemini 3.8 Flash is cheaper on both: 1.7× input, 2.7× output.

Where to run it

3 hosts, cheapest first

Gemini 3.8 Flash2 hosts
HostInOutContextUptime
Google Vertex AI$0.38 in·$1.88 out·1M·82.1% upGoogle AI Studio$0.75 in·$3.75 out·1M·99.9% up
GPT-5.1-Codex1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up

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

Writing DNA

Style Comparison

Similarity
60%
Gemini 3.8 Flash
GPT-5.1-Codex
63%Vocabulary70%
20wSentence Length17w
0.17Hedging0.39
4.0Bold3.4
2.4Lists3.5
0.01Emoji0.00
0.84Headings0.50
0.06Transitions0.38
Based on 27 + 14 text responses
Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Against the newest arrivals

Gemini 3.8 Flash logoGPT-6 Astra Pro logo
Gemini 3.8 Flash vs GPT-6 Astra ProLanded Sep 2026
GPT-5.1-Codex logoGPT-6 Astra logo
GPT-5.1-Codex vs GPT-6 AstraLanded Sep 2026
Gemini 3.8 Flash logoClaude Fable 5.1 logo
Gemini 3.8 Flash vs Claude Fable 5.1Landed Sep 2026
GPT-5.1-Codex logoMuse Spark 1.3 logo
GPT-5.1-Codex vs Muse Spark 1.3Landed Sep 2026
Gemini 3.8 Flash logoHy4 Preview logo
Gemini 3.8 Flash vs Hy4 PreviewLanded Sep 2026
GPT-5.1-Codex logoMuse Spark 1.3 Contributor logo
GPT-5.1-Codex vs Muse Spark 1.3 ContributorLanded Sep 2026
Gemini 3.8 Flash logoMercury 2.5 Preview logo
Gemini 3.8 Flash vs Mercury 2.5 PreviewLanded Sep 2026
GPT-5.1-Codex logoGranite 4.2 8B logo
GPT-5.1-Codex vs Granite 4.2 8BLanded Sep 2026

Same lab, same size, long tail

Gemini 3.8 Flash logoGemini 3.7 Flash logo
Gemini 3.8 Flash vs Gemini 3.7 FlashSame lab
Gemini 3.8 Flash logoGemini 3.6 Flash logo
Gemini 3.8 Flash vs Gemini 3.6 FlashSame lab
GPT-5.1-Codex logoGPT-6 Astra Pro logo
GPT-5.1-Codex vs GPT-6 Astra ProSame lab
GPT-5.1-Codex logoGPT-5.6 Luna logo
GPT-5.1-Codex vs GPT-5.6 LunaSame lab
GPT-5.1-Codex logoMiniMax M3 logo
GPT-5.1-Codex vs MiniMax M3New provider
Gemini 3.8 Flash logoMistral Large logo
Gemini 3.8 Flash vs Mistral LargeSame size
Gemini 3.8 Flash logoMistral Large 2 logo
Gemini 3.8 Flash vs Mistral Large 2Same size
Gemini 3.8 Flash logoMistral Large 3 2512 logo
Gemini 3.8 Flash vs Mistral Large 3 2512New provider

Model pages

Gemini 3.8 Flash logo
Gemini 3.8 Flash58 outputs, specs and price
GPT-5.1-Codex logo
GPT-5.1-Codex53 outputs, specs and price
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed