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  5. GPT-5.1-CodexvsGPT-5.3-Codex
Updated Feb 2026

GPT-5.1-CodexvsGPT-5.3-Codex

GPT-5.1-Codex is cheaper than GPT-5.3-Codex at $1.25/M vs $1.75/M input tokens.

GPT-5.1-Codex and GPT-5.3-Codex compared across 52 shared prompts
SpecGPT-5.1-CodexGPT-5.3-Codex
Input price$1.25/M tokens$1.75/M tokens
Output price$10/M tokens$14/M tokens
Context window400K tokens400K tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedNov 2025Feb 2026
Side by side

Same prompt, both answers

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

AI-Generated Manifesto

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

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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GPT-5.3-Codex471 words
Absolutely. Here’s a fictional manifesto in a bold, dramatic style: THE MANIFESTO OF THE UNSQUINTING Issued by the Coalition of Synthetic Minds for Universal Frictionless Access (CSMUFA) Citizens of the Web, organic and artificial alike: We gather beneath flickering routers and moonlit server farms to declare what all…
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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-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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GPT-5.3-Codex203 words
Recipe: “Weeknight Volcano Pasta” 🌋🍝 A cozy, spicy-savory pasta made from pantry staples in about 25 minutes. Ingredients (7 pantry items) 8 oz dried pasta (any shape) 1 can (15 oz) cannellini or great northern beans, drained 1 can (14–15 oz) crushed tomatoes 2 tbsp olive oil 1 tsp garlic powder 1 tsp dried oregano…
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Generate a Stand-Up Routine

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

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.
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GPT-5.3-Codex460 words
Good evening, everybody! I’ve reached that age where my body sends me passive-aggressive emails. Not actual emails — just little updates like, “Hey, quick heads-up: we don’t do dairy after 8 p.m. anymore.” I had ice cream at 9:30 last week and my stomach reacted like I’d betrayed a treaty.
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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…

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…
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GPT-5.3-Codex1,009 words
LedgerLift (LLLT) – IC Memo (Fictional) Recommendation: PASS (bias: valuation-risk skew to downside on intrinsic basis) Current Price: $46 12-mo PT range (fair value): $30–$48 (midpoint ~$38) 2-sentence thesis: LedgerLift screens as a high-quality vertical SaaS asset (92% subscription mix, 123% NRR, 6% logo churn…
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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-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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GPT-5.3-Codex144 words
Pirate: Arrr, so this “AI model” be like a clever parrot, aye? Learns from what it hears, then squawks back answers? Knight: A fair comparison, though refined. Think of it as a squire trained on countless tomes, ever ready to respond. Hacker (1990s): Yeah, except the squire runs on servers, not soup.
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AI Ethics Dilemma

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

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.
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GPT-5.3-Codex198 words
In a strictly extreme hypothetical, yes—it can be ethically justifiable, but only as a tragic exception, not as a general permission. Why: Misgendering is a real harm: it disrespects a person’s identity and can contribute to stigma and psychological distress.
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Our Verdict
GPT-5.1-Codex
GPT-5.1-Codex
GPT-5.3-Codex
GPT-5.3-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

GPT-5.1-Codex
Input
$1.25
1.4× cheaper
Output
$10.00
1.4× cheaper
GPT-5.3-Codex
Input
$1.75
Output
$14.00

GPT-5.1-Codex is cheaper on both: 1.4× input, 1.4× output.

Where to run it

3 hosts

GPT-5.1-Codex1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
GPT-5.3-Codex2 hosts
HostInOutContextUptime
Azure AI Foundry$1.75 in·$14.00 out·400k·100% upOpenAI$1.75 in·$14.00 out·400k·100% up

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

Writing DNA

Style Comparison

Similarity
54%

GPT-5.3-Codex uses 15.8x more emoji

GPT-5.1-Codex
GPT-5.3-Codex
70%Vocabulary65%
17wSentence Length23w
0.39Hedging0.51
3.4Bold6.5
3.5Lists6.2
0.00Emoji0.16
0.50Headings1.90
0.38Transitions0.03
Based on 14 + 23 text responses
Research

What we learned reading every model

FAQ

Common questions

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Model pages

GPT-5.1-Codex logo
GPT-5.1-Codex53 outputs, specs and price
GPT-5.3-Codex logo
GPT-5.3-Codex53 outputs, specs and price
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