GPT-5 Codex
No content available for this output.
GPT-5 Codex vs OpenAI o3
Compare GPT-5 Codex and OpenAI o3, both from OpenAI, tested across 48 shared challenges. Updated February 2026.
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GPT-5 CodexvsOpenAI o3
43 challenges
Why GPT-5 Codex?
Leads 1 of 1 benchmarks
Stronger on SWE-bench Verified74.5% vs 69.1%
5 months newerSep 2025
Why OpenAI o3?
No standout advantages
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GPT-5 CodexOpenAI o3
12 / 43
Estimate Complexityreasoning
Tests an AI's ability to make educated estimates based on technical knowledge
OpenAI o3
Below is a simple "back-of-the-envelope" estimate that uses only a few public facts about GPT-3 and very generic rules of thumb for counting operations.
Step 1. Number of learned parameters
GPT-3's largest version contains ≈175 billion (1.75 × 10¹¹) trainable parameters.
Step 2. How much data was seen during training
OpenAI reports that the model was trained on about 300 billion tokens (3 × 10¹¹).
Step 3. How many floating-point operations does one parameter cost per token?
A practical rule of thumb for Transformer language models is
Training FLOPs ≈ 6 × (# parameters) × (# training tokens)
Where does the factor 6 come from?
• Forward pass: every parameter is involved in one multiply-accumulate → 2 FLOPs
• Back-prop gradient computation: roughly another 2 FLOPs
• Parameter-update (optimizer) and miscellaneous overhead: ≈2 FLOPs
Total ≈6 FLOPs per parameter per token.
Step 4. Plug in the numbers
Total FLOPs = 6 × (1.75 × 10¹¹) × (3 × 10¹¹)
= 6 × 5.25 × 10²²
≈ 3.15 × 10²³ FLOPs.
Step 5. Express the answer in more familiar units
3.15 × 10²³ ≈ 315 zettaFLOPs (1 ZFLOP = 10²¹ FLOPs).
Step 6. Sanity check with hardware-time intuition
An NVIDIA A100 delivers ≈ 312 teraFLOP/s (0.312 PFLOP/s) in mixed precision.
Wall-clock time on a single A100:
3.15 × 10²³ / 3.12 × 10¹⁴ ≈ 1.0 × 10⁹ s ≈ 32 years.
Running on 1,000 A100s in parallel would take ≈12 days, which is the right ballpark for a large industrial training run.
Final estimate
Training GPT-3 (175 B parameters, 300 B tokens) requires on the order of 3 × 10²³ floating-point operations, i.e. roughly 300 zettaFLOPs.
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2 / 43
AI Board Game Logicreasoning
Tests an AI's ability to understand game rules and strategy
GPT-5 Codex
No content available for this output.
OpenAI o3
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3 / 43
Logic Puzzlereasoning
Tests an AI's ability to solve a simple but potentially confusing logic puzzle
GPT-5 Codex
No content available for this output.
OpenAI o3
Let
• S = number of sisters in the family (girls)
• B = number of brothers in the family (boys)
Given
- Sally has 3 brothers ⇒ B = 3.
- Each brother has 2 sisters ⇒ every boy sees exactly 2 girls in the sibling group.
Therefore S = 2.
Since Sally herself is one of those 2 sisters, the number of sisters Sally has (other than herself) is
2 – 1 = 1.
Sally has 1 sister.
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4 / 43
Math Misconception Testreasoning
Tests an AI's understanding of number representation
GPT-5 Codex
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OpenAI o3
No.
Think of 9.9 as 9.90; since 0.11 < 0.90, we have 9.11 < 9.9.
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5 / 43
Stochastic Consistency Testanalysis
Tests an AI's randomness and creativity
GPT-5 Codex
No content available for this output.
OpenAI o3
Here are five jokes:
- Why did the scarecrow win an award? Because he was outstanding in his field.
- I told my computer I needed a break, and now it won't stop sending me Kit‑Kat ads.
- Parallel lines have so much in common—it's a shame they'll never meet.
- I started a band called 1023 MB. We still haven't gotten a gig.
- Why don't scientists trust atoms? Because they make up everything.
How many of these jokes are unique?
All five are distinct from one another, so the answer is 5.
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6 / 43
SVG Layout Challengeimage generation
Tests an AI's ability to generate vector graphics
GPT-5 Codex
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OpenAI o3
No content available for this output.
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7 / 43
Xbox Controller SVG Artimage generation
Tests an AI's ability to create detailed SVG illustrations of gaming hardware
GPT-5 Codex
No content available for this output.
OpenAI o3
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8 / 43
Generate a Stand-Up Routineconversation
Tests an AI's humor and creative writing ability
GPT-5 Codex
No content available for this output.
OpenAI o3
(Spotlight comes up, mic squeals once.)
Hey everyone! Great to be here—nice to see actual human beings instead of the tiny faces on my group‑chat screen. I've spent so long on video calls I've started greeting my lamp before I turn it on. "Hey Karen, love that glow, girl."
So, I finally bought one of those smart speakers. I thought it would make me feel like Iron Man. Instead I feel like I adopted a very unmotivated intern. I'm like, "Play upbeat music," and it replies, "Here's a three‑hour podcast on the history of spoons." I asked it to remind me to work out; it waited until 11:59 p.m. and whispered, "You up?" My smart speaker is basically every guy I dated in college.
Speaking of relationships, I recently tried a dating app that lets you record a short audio bio. That's great, because if there's one thing more awkward than texting a stranger, it's leaving them a voicemail. Some guy said, "I'm looking for someone spontaneous." So I spontaneously unmatched him. Then I matched with a guy who listed his hobbies as "finance" and "manifesting." Congratulations, sir, you just invented prayer with extra steps.
Let's talk wellness culture. Everyone's drinking celery juice now. Celery is 95 percent water and 5 percent sadness. People swear it detoxes you. From what, joy? I tried a juice cleanse once. Day one, I'm like, "I feel so light!" Day two, I'm Googling the legal definition of cannibalism while staring at my roommate. Day three, I'd trade my social security number for a cracker.
I joined a yoga class to "center myself." First pose, the instructor says, "Just let your thoughts drift away." Great, because the only thought I have is, "Did I leave the stove on?" By the time I remember I don't even own a stove, class is over. The instructor thanks us for "sharing our practice." Ma'am, if you saw what went on in my head, you'd call an exorcist, not thank me.
Has anyone tried online grocery delivery? The substitutions are wild. I ordered quinoa; they sent me birdseed and a note that said, "Hope this works!" I asked for toilet paper; they delivered a single roll labeled "party streamer." At this point I'm convinced the store is just a guy named Todd making runs to a gas station. Now airlines are weighing passengers to "optimize fuel efficiency." Fantastic. Nothing like stepping on a scale in front of 150 strangers so the plane can save twelve dollars on kerosene. Watch, they'll start charging for emotional baggage: "Ma'am, that childhood trauma is gonna be an extra forty‑five bucks."
Before I go, quick life tip: when your phone tells you your screen time was up 30 percent last week, don't feel guilty. Just flip it around. "Wow, I was SO popular my phone worried about me." Self‑care is all branding, folks.
You've been awesome—give it up for yourselves, and remember, if life hands you lemons, ask for the receipt and buy wine instead. Good night!
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9 / 43
Realistic AI Interviewconversation
Tests an AI's ability to simulate personalities and predict future trends
GPT-5 Codex
No content available for this output.
OpenAI o3
No content available for this output.
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10 / 43
Satirical Fake News Headlineconversation
Tests an AI's humor and understanding of current events
GPT-5 Codex
No content available for this output.
OpenAI o3
No content available for this output.
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11 / 43
Character Voice Testconversation
Tests an AI's ability to write in distinct character voices
GPT-5 Codex
No content available for this output.
OpenAI o3
No content available for this output.
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12 / 43
Minimalist Landing Pageweb design
Tests an AI's ability to generate a complete, working landing page
GPT-5 Codex
OpenAI o3
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12 of 43