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  5. GPT-5.3-CodexvsGPT-6 Astra
Updated Sep 2026

GPT-5.3-CodexvsGPT-6 Astra

GPT-5.3-Codex is cheaper than GPT-6 Astra at $1.75/M vs $10/M input tokens.

GPT-5.3-Codex and GPT-6 Astra compared across 53 shared prompts
SpecGPT-5.3-CodexGPT-6 Astra
Input price$1.75/M tokens$10/M tokens
Output price$14/M tokens$50/M tokens
Context window400K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedFeb 2026Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 53 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…

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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GPT-6 Astra200 words
Cinnamon Hug Cookies Buttery cookies with crisp edges, soft centers, and a cozy cinnamon flavor. Makes: About 20 cookies Prep: 10 minutes Cook: 10–12 minutes per batch Ingredients — exactly 7 1½ cups all-purpose flour ¾ cup granulated sugar, divided ½ cup salted butter, softened 1 large egg 1 teaspoon vanilla extract ½…
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Generate a Stand-Up Routine

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

GPT-5.3-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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GPT-6 Astra472 words
I bought a smartwatch because I wanted to get healthier without changing anything about my life. That’s the dream, right? Same habits, but now there’s a graph. The watch congratulates me for standing up. That’s where I am physically. Getting out of a chair is an achievement with a little fireworks animation.
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

GPT-5.3-Codex78 words
Sure—here are 5 jokes: Why don’t skeletons fight each other? They don’t have the guts. I told my computer I needed a break… Now it won’t stop sending me KitKat ads. Why did the math book look sad? It had too many problems. I used to play piano by ear… Now I use my hands. Why did the scarecrow win an award?
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GPT-6 Astra76 words
My calendar is afraid of commitment—its days are numbered. I bought a treadmill for my cat. Now I own a very expensive nap conveyor. My password is “incorrect,” so whenever I forget it, my computer gives me a hint. I asked the librarian where the books on denial were. She said, “We don’t have those.” Nice try.
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Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

GPT-5.3-Codex429 words
Great concept, but three claims stand out as especially weak from an investor diligence perspective: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.” (Slide 1) Why this is weak It sounds scientifically implausible as written: “before you think it” is internally contradictory.
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GPT-6 Astra696 words
The three weakest claims are the 94% decoding accuracy, the $180B TAM, and the promise to predict text “before you think it.” These are central to the investment case but lack the definitions or evidence needed to evaluate them. “Decode neural patterns into text with 94% accuracy. Works with any language, any device.”
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Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

GPT-5.3-Codex551 words
Below is a clean LBO build using your assumptions only ($ in millions). Entry math (end FY2025) EV = \(12.0 \times 120 = 1,440.0\) Fees = \(2.0\% \times 1,440.0 = 28.8\) Total uses = \(1,468.8\) Debt at close (5.5x EBITDA): Term Loan = \(4.0 \times 120 = 480.0\) Mezz = \(1.5 \times 120 = 180.0\) Total debt = 660.0…
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GPT-6 Astra560 words
Entry capitalization and operating model All figures in $m. Interest is calculated on beginning-of-year debt balances. Term Loan amortization is 1% of its original principal, or $4.8m annually; remaining cash flow is swept to the Term Loan at year-end. Mezzanine PIK accrues annually.
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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-5.3-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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GPT-6 Astra121 words
Pirate: Arrr, this AI model writes sea shanties, plots me voyages, and never asks for a share o’ the booty! Knight: But can it be trusted? I asked it to name my ancestors, and it invented Sir Geoffrey the Surprisingly Tall. Hacker: Classic hallucination, dude. Fluent output doesn’t mean verified data.
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Our Verdict
GPT-6 Astra
GPT-6 Astra
GPT-5.3-Codex
GPT-5.3-CodexRunner-up

Not enough votes to call it. On the specs, GPT-6 Astra has the edge: newer, bigger context window.

GPT-5.3-Codex costs 3.6x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.3-Codex
Input
$1.75
5.7× cheaper
Output
$14.00
3.6× cheaper
GPT-6 Astra
Input
$10.00
Output
$50.00

GPT-5.3-Codex is cheaper on both: 5.7× input, 3.6× output.

Where to run it

4 hosts

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·99.9% up
GPT-6 Astra2 hosts
HostInOutContextUptime
Azure AI Foundry$10.00 in·$50.00 out·1.1M·98.3% upOpenAI$10.00 in·$50.00 out·1.1M·99.4% up

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

Writing DNA

Style Comparison

Similarity
49%

GPT-5.3-Codex uses 4.3x more emoji

GPT-5.3-Codex
GPT-6 Astra
65%Vocabulary62%
23wSentence Length15w
0.51Hedging0.87
6.5Bold4.0
6.2Lists2.3
0.16Emoji0.04
1.90Headings0.77
0.03Transitions0.10
Based on 23 + 27 text responses
Research

What we learned reading every model

FAQ

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Model pages

GPT-5.3-Codex logo
GPT-5.3-Codex53 outputs, specs and price
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GPT-6 Astra58 outputs, specs and price
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