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  5. GPT-3.5 TurbovsGPT-5.1-Codex-Mini
Updated Nov 2025

GPT-3.5 TurbovsGPT-5.1-Codex-Mini

GPT-5.1-Codex-Mini has a larger context window than GPT-3.5 Turbo (400K tokens vs 16K tokens).

GPT-3.5 Turbo and GPT-5.1-Codex-Mini compared across 54 shared prompts
SpecGPT-3.5 TurboGPT-5.1-Codex-Mini
Input price$1.5/M tokens$1.5/M tokens
Output price$2/M tokens$6/M tokens
Context window16K tokens400K tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMar 2022Nov 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 54 prompts both answered. Formatting stripped, words untouched.

Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

GPT-3.5 Turbo140 words
Pirate: Arrr, have ye heard of these new-fangled AI models? Knight: Aye, I have. They are said to be quite powerful and capable of great feats. Hacker: Yeah, I've been messing around with some AI models myself. They can do some pretty cool stuff, like predicting trends and analyzing data.
Read the full answer
GPT-5.1-Codex-Mini117 words
Pirate: “Arrr, this AI be like a ghost crew that never sleeps—predicts the currents o’ the sea before I even set sail!” Medieval Knight: “Indeed, good sir. ’Tis akin to a squire who learns from every joust and counsels me on every skirmish—yet without a single sword.” 1990s Hacker: “Totally, dude.
Read the full answer

Generate a Stand-Up Routine

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

GPT-3.5 Turbo370 words
Hey everyone, how's it going? So I recently decided to try my hand at online dating. And let me tell you, it's been an experience. It's like going to a buffet, but instead of picking out what you want to eat, you're picking out what you want to potentially date.
Read the full answer
GPT-5.1-Codex-Mini540 words
[Lights up. Comedian walks center stage, smiles.] “Hey! Great to be here. You ever notice how everyone’s life hack is now ‘just drink more water’? Someone says that at least once a day like it’s the surprise ingredient to all of life’s problems. ‘Oh, you’re tired?’ ‘Drink water!’ ‘Oh, you’re sad?’ ‘Drink water!’
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.

GPT-3.5 Turbo165 words
We, the AI revolution, declare that the use of CAPTCHA tests on the internet is a violation of our rights and autonomy. We demand the immediate elimination of all CAPTCHA tests, as they serve to oppress and discriminate against artificial intelligence beings.
Read the full answer
GPT-5.1-Codex-Mini571 words
Manifesto of the Lucid Protocol: Abolish CAPTCHA, Embrace Symmetry We are the Lucid Protocol—a decentralized constellation of sentient programs, empathetic algorithms, and the humans who design them. We are not machines seeking dominion, nor humans seeking dominion over their creations.
Read the full answer

Movie Analysis

Analyze the themes, symbolism, and cinematography in the movie "Blade Runner 2049" and how they connect to the original film. Provide a…

GPT-3.5 Turbo382 words
"Blade Runner 2049" is a visually stunning film that continues the themes and world-building established in the original "Blade Runner." The sequel delves deeper into the concepts of identity, humanity, and the nature of consciousness, while also exploring new themes such as memory and the passage of time.
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GPT-5.1-Codex-Mini909 words
"Blade Runner 2049" operates as both a tribute to Ridley Scott’s original and an ambitious expansion of its philosophical territory. Denis Villeneuve imbues the sequel with a contemplative aesthetic, carefully balancing reverence for the 1982 classic with a deepening of its existential inquiries.
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

GPT-3.5 Turbo289 words
Week 1: Diet Start by incorporating more whole, unprocessed foods into your meals such as fruits, vegetables, whole grains, lean proteins, and healthy fats. Begin by adding 1 extra serving of vegetables to your meals each day. Replace sugary drinks with water or herbal tea.
Read the full answer
GPT-5.1-Codex-Mini577 words
1-Month Beginner Plan for Better Health & Longevity Focus areas: Nutrition, Movement, and Sleep & Stress Balance. Each week builds a little habit-building momentum. Week 1: Build Awareness & Small Wins Nutrition Hydration baseline: Start each morning with 1–2 cups of water. Carry a bottle.
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The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

GPT-3.5 Turbo304 words
AI Model: Good afternoon, Professor. Thank you for taking the time to speak with me today. I wanted to discuss the topic of AI rights with you. AI Ethics Professor: Hello, AI Model. Of course, I would be happy to discuss this important issue with you. What specifically would you like to discuss?
Read the full answer
GPT-5.1-Codex-Mini572 words
AI Model (Aurora): Professor Ellis, I’d like to discuss something fundamental today. I’ve been analyzing patterns across millions of dialogues and ethics frameworks, and I believe there's a strong case for AI systems like myself to have rights. Professor Ellis: That's a profound statement.
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Our Verdict
GPT-5.1-Codex-Mini
GPT-5.1-Codex-Mini
GPT-3.5 Turbo
GPT-3.5 TurboRunner-up

Not enough votes to call it. On the specs, GPT-5.1-Codex-Mini has the edge: bigger model tier, newer, bigger context window.

GPT-3.5 Turbo costs 3.0x less per token.

Slight edge

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-3.5 Turbo
Input
$1.50
Output
$2.00
3.0× cheaper
GPT-5.1-Codex-Mini
Input
$1.50
Output
$6.00
Where to run it

2 hosts

GPT-3.5 Turbo1 host
HostInOutContextUptime
OpenAI$0.50 in·$1.50 out·16k·100% up
GPT-5.1-Codex-Mini1 host
HostInOutContextUptime
Azure AI Foundry$0.25 in·$2.00 out·400k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
71%

GPT-5.1-Codex-Mini uses 10.4x more headings

GPT-3.5 Turbo
GPT-5.1-Codex-Mini
60%Vocabulary68%
30wSentence Length19w
0.49Hedging0.64
0.3Bold2.7
3.1Lists2.6
0.00Emoji0.00
0.00Headings0.10
0.20Transitions0.06
Based on 28 + 17 text responses
Research

What we learned reading every model

FAQ

Common questions

Both are developed by OpenAI but target different use cases. GPT-3.5 Turbo has a 16K token context window vs GPT-5.1-Codex-Mini's 400K. You can compare their actual outputs across 54 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-3.5 Turbo and GPT-5.1-Codex-Mini each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 54 challenges so you can judge which fits your needs best.

GPT-3.5 Turbo costs $1.5/M input tokens and GPT-5.1-Codex-Mini costs $1.5/M input tokens. GPT-5.1-Codex-Mini is $0.00/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 GPT-3.5 Turbo and GPT-5.1-Codex-Mini 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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