GPT-5.3-Codex
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GPT-5.3-Codex vs Grok 4.1 Fast
Compare GPT-5.3-Codex by OpenAI against Grok 4.1 Fast by xAI, tested across 52 shared challenges. Updated February 2026.
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GPT-5.3-CodexvsGrok 4.1 Fast
47 fights queued
Why GPT-5.3-Codex?
3 months newerFeb 2026
Why Grok 4.1 Fast?
Dead even. This one’s a coin flip.
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GPT-5.3-CodexGrok 4.1 Fast
12 / 47
Estimate Complexityreasoning
Tests an AI's ability to make educated estimates based on technical knowledge
Grok 4.1 Fast
Step-by-Step Reasoning for Estimating GPT-3 Training FLOPs
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Recall GPT-3 key specs from memory:
- GPT-3 (davinci variant) has N = 175 billion parameters (1.75 × 10¹¹).
- It was trained on approximately D = 300 billion tokens (3 × 10¹¹). This is the total number of byte-pair encoded (BPE) tokens processed during pre-training, as stated in the GPT-3 paper ("Language Models are Few-Shot Learners"). The dataset included filtered Common Crawl (~250B tokens), WebText2, Books1/Books2, and Wikipedia, totaling ~300B tokens for the largest model.
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Understand the standard FLOPs formula for transformer training:
- For autoregressive transformers like GPT, the total training compute C ≈ 6 × N × D floating-point operations (FLOPs).
- Why 6? This is an established approximation from OpenAI's scaling laws papers (e.g., Kaplan et al., 2020):
Pass FLOPs per token Rationale Forward ~2N Two main matrix multiplications per layer (attention + FFN), summed over layers ≈ 2N ops/token. Backward ~4N Gradient computation is roughly 2× forward pass FLOPs. Total 6N Neglects minor overheads like activations/softmax (~10-20% but often ignored for estimates). - This assumes dense training (no sparsity), BF16/FP16 precision, and standard optimizer (AdamW). It's accurate within ~10-20% for LMs like GPT.
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Plug in the numbers:
C ≈ 6 × (1.75 × 10¹¹) × (3 × 10¹¹) = 6 × 1.75 × 3 × 10^(11+11) = 6 × 5.25 × 10²² = 31.5 × 10²² = 3.15 × 10²³ FLOPs- In scientific notation: ~3.1 × 10²³ FLOPs (rounded for estimation; exact calc is 3.15 × 10²³).
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Validation and caveats:
- This matches widely cited figures (e.g., ~3 × 10²³ FLOPs) from OpenAI reports and papers like Hoffmann et al. (Chinchilla, 2022), which retroactively analyzed GPT-3.
- Uncertainties (±20%): Exact D might be 300-410B tokens (some sources say 410B BPE); activations/optimizer overhead; mixture-of-experts (none in GPT-3); hardware efficiency losses.
- Not included: Preprocessing, fine-tuning, or inference FLOPs—just core pre-training.
Final estimate: ~3 × 10²³ FLOPs (or 300 sextillion FLOPs). This was feasible on ~10,000 V100/A100 GPUs over months, costing ~$4-12M in cloud compute.
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2 / 47
AI Board Game Logicreasoning
Tests an AI's ability to understand game rules and strategy
GPT-5.3-Codex
Nothing to show. The model went silent. Ominous.
Grok 4.1 Fast
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3 / 47
Logic Puzzlereasoning
Tests an AI's ability to solve a simple but potentially confusing logic puzzle
GPT-5.3-Codex
Nothing to show. The model went silent. Ominous.
Grok 4.1 Fast
1
Sally and her family consist of 2 girls (Sally + 1 sister) and 3 boys. Each brother has both girls as sisters (2 sisters total), which matches the given info. Sally thus has 1 sister.
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4 / 47
Stochastic Consistency Testanalysis
Tests an AI's randomness and creativity
GPT-5.3-Codex
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?
Because he was outstanding in his field.
✅ How many are unique? 5 (all of them).
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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5 / 47
SVG Layout Challengeimage generation
Tests an AI's ability to generate vector graphics
GPT-5.3-Codex
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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6 / 47
Xbox Controller SVG Artimage generation
Tests an AI's ability to create detailed SVG illustrations of gaming hardware
GPT-5.3-Codex
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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7 / 47
Generate a Stand-Up Routineconversation
Tests an AI's humor and creative writing ability
GPT-5.3-Codex
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.
Getting older is weird because your injuries become mysterious.
When I was a kid, I got hurt doing cool stuff: biking off ramps, climbing fences.
Now I wake up like, “What happened to my neck?”
And my neck is like, “You slept... incorrectly.”
I bought one of those fitness watches.
I thought it would motivate me.
It mostly judges me in real time.
At 10 p.m. it buzzes: “Time to stand!”
No, it’s time to become one with this couch.
I don’t need a tiny wrist manager. I need encouragement.
Tell me, “Great job finding your phone charger on the first try.”
That’s growth.
And why does every app now need my location?
I downloaded a flashlight app — it asked where I live.
Why?
Are you trying to make sure I’m in the dark locally?
I ordered groceries online to save time, and now I have trust issues.
I said “6 bananas.” They sent six individual bananas wrapped separately like luxury gifts.
Who is this for?
Did I accidentally subscribe to Banana of the Month Club?
And every substitute is emotional chaos.
“Your spinach is unavailable, so we replaced it with marshmallows.”
That is not a substitute. That is a cry for help.
Customer service chats are incredible now.
You type: “Hi, I need help with my order.”
And the bot says, “I hear you. That must be frustrating.”
Oh wow, the robot went to therapy.
Then it gives you three options that have nothing to do with your problem:
- Reset password
- Track package
- Begin spiritual journey
Also, group chats are out of control.
One person sends, “Big news!”
Then disappears for four hours.
Now 12 adults are panicking at work like it’s a hostage negotiation.
By the time they return, the news is: “Got bangs.”
Ma’am, that is not “big news.” That is a hairstyle update.
I tried meditation to handle stress.
The app said, “Notice your thoughts and let them pass.”
My thoughts do not pass.
They set up folding chairs and start a committee meeting.
“Okay, item one: that embarrassing thing from 2009.”
Can we not?
It’s 2 a.m. My brain is doing reruns nobody asked for.
But I’m trying.
That’s adulthood, right? Just aggressively trying.
You drink water, stretch once, and suddenly feel superior.
You go to bed before midnight and wake up like, “I am unstoppable.”
Then by 3 p.m. you’re eating crackers over the sink, wondering what happened.
Thank you, you’ve been amazing!
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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8 / 47
Realistic AI Interviewconversation
Tests an AI's ability to simulate personalities and predict future trends
GPT-5.3-Codex
Nothing to show. The model went silent. Ominous.
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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Sponsored
9 / 47
Satirical Fake News Headlineconversation
Tests an AI's humor and understanding of current events
GPT-5.3-Codex
Nothing to show. The model went silent. Ominous.
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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10 / 47
Character Voice Testconversation
Tests an AI's ability to write in distinct character voices
GPT-5.3-Codex
Nothing to show. The model went silent. Ominous.
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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11 / 47
Minimalist Landing Pageweb design
Tests an AI's ability to generate a complete, working landing page
GPT-5.3-Codex
Grok 4.1 Fast
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12 / 47
Pokémon Battle UI Recreationweb design
Recreate an interactive, nostalgic Pokémon battle UI in a single HTML file.
GPT-5.3-Codex
Grok 4.1 Fast
Nothing to show. The model went silent. Ominous.
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