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

GPT-3.5 TurbovsGPT-5.1-Codex

GPT-5.1-Codex is cheaper than GPT-3.5 Turbo at $1.25/M vs $1.5/M input tokens.

GPT-3.5 Turbo and GPT-5.1-Codex compared across 52 shared prompts
SpecGPT-3.5 TurboGPT-5.1-Codex
Input price$1.5/M tokens$1.25/M tokens
Output price$2/M tokens$10/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 52 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.

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-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

Stochastic Consistency Test

Generate 5 jokes. How many are unique?

GPT-3.5 Turbo77 words
Why did the scarecrow win an award? Because he was outstanding in his field! How does a penguin build its house? Igloos it together! I used to play piano by ear, but now I use my hands like everyone else. Why couldn't the bicycle find its way home? It lost its bearings! I told my wife she should embrace her mistakes.
Read the full answer
GPT-5.1-Codex71 words
Here are 5 jokes: Why don’t scientists trust atoms? Because they make up everything. I told my computer I needed a break—it said “No problem, I’ll go to sleep.” I’m reading a book about anti-gravity. It’s impossible to put down. Why did the scarecrow become a successful motivational speaker?
Read the full answer

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-Codex492 words
Here’s a simple, beginner-friendly 1-month plan focused on three key areas—Nutrition, Movement, and Rest & Recovery—to kickstart better health and longevity. Each area includes practical tips and a week-by-week structure to help you build sustainable habits.
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.
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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.
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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…

GPT-3.5 Turbo134 words
Recipe: Honey Mustard Chicken Bake Ingredients: 4 boneless, skinless chicken breasts 1/2 cup honey 1/4 cup Dijon mustard 1 tablespoon olive oil 1 teaspoon garlic powder Salt and pepper to taste 1/2 cup shredded cheddar cheese Instructions: Preheat the oven to 375°F.
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…
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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.
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GPT-5.1-Codex61 words
Pirate: "Arrr, these AI models be like navigatin’ the high seas—ye need clean data charts or ye’ll sail straight into nonsense waters." Knight: "Indeed! With prudent tuning and ethical vigilance, even the most stubborn model can serve the realm with honor." 1990s Hacker: "Totally!
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Our Verdict
GPT-5.1-Codex
GPT-5.1-Codex
GPT-3.5 Turbo
GPT-3.5 TurboRunner-up

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

GPT-3.5 Turbo costs 5.0x 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
5.0× cheaper
GPT-5.1-Codex
Input
$1.25
1.2× cheaper
Output
$10.00

GPT-5.1-Codex wins input (1.2× cheaper)·GPT-3.5 Turbo wins output (5.0× cheaper)

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-Codex1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up

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

Writing DNA

Style Comparison

Similarity
73%

GPT-5.1-Codex uses 50.1x more headings

GPT-3.5 Turbo
GPT-5.1-Codex
60%Vocabulary70%
30wSentence Length17w
0.49Hedging0.39
0.3Bold3.4
3.1Lists3.5
0.00Emoji0.00
0.00Headings0.50
0.20Transitions0.38
Based on 28 + 14 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's 400K. You can compare their actual outputs across 52 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 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 52 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 costs $1.25/M input tokens. GPT-5.1-Codex is $0.25/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 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

GPT-3.5 Turbo logo
GPT-3.5 Turbo58 outputs, specs and price
GPT-5.1-Codex logo
GPT-5.1-Codex53 outputs, specs and price
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