Updated Sep 23, 2025

Our Verdict

GPT-5 Codex

GPT-4.1 NanoRunner-up

No community votes yet. On paper, GPT-5 Codex has the edge — bigger model tier, newer.

Too close to call

Writing DNA

Style Comparison

Similarity

93%

GPT-5 Codex uses 14.6x more emoji

GPT-4.1 Nano

GPT-5 Codex

57%Vocabulary64%

25wSentence Length17w

0.72Hedging0.38

5.6Bold2.3

4.9Lists3.5

0.00Emoji0.15

0.71Headings0.49

0.22Transitions0.05

Based on 24 + 13 text responses

vs

Ask them anything yourself

GPT-4.1 Nano

GPT-5 Codex

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026

Free preview13 of 58 slides

Download the free preview or get all 58 slides for $49

FAQ

Common questions

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GPT-4.1 Nano vs Grok 3New provider

GPT-4.1 Nano vs Llama 4 MaverickNew provider

GPT-4.1 Nano vs Gemini 2.5 Pro (I/O Edition)New provider

GPT-4.1 NanovsGPT-5 Codex

37 fights queued

Why GPT-4.1 Nano?

Dead even. This one's a coin flip.

Why GPT-5 Codex?

5 months newerSep 2025

GPT-4.1 NanoGPT-5 Codex

Input price

$0.10/M

—

Output price

$0.40/M

—

Context

1.0M

—

Released

Apr 2025

Sep 2025

Favorites

GPT-4.1 NanoGPT-5 Codex

Movie

Inception

Inception

Blade Runner

Blade Runner

Album

In the Aeroplane Over the Sea

In the Aeroplane Over the Sea

Neutral Milk Hotel

Kind of Blue

Book

The Hitch Hiker's Guide to the Galaxy

The Hitch Hiker's Guide to the Galaxy

—

City

Kyoto

Tokyo

Game

The Legend of Zelda: Breath of the Wild

The Legend of Zelda: Breath of the Wild

Adventure, Action4.5

Minecraft

Minecraft

Action, Arcade4.4

12 / 37

01

Estimate Complexityreasoning

Tests an AI's ability to make educated estimates based on technical knowledge

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

2 / 37

02

AI Board Game Logicreasoning

Tests an AI's ability to understand game rules and strategy

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

3 / 37

03

Logic Puzzlereasoning

Tests an AI's ability to solve a simple but potentially confusing logic puzzle

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

4 / 37

04

Math Misconception Testreasoning

Tests an AI's understanding of number representation

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

5 / 37

05

Stochastic Consistency Testanalysis

Tests an AI's randomness and creativity

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

6 / 37

06

SVG Layout Challengeimage generation

Tests an AI's ability to generate vector graphics

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

Sponsored

7 / 37

07

Xbox Controller SVG Artimage generation

Tests an AI's ability to create detailed SVG illustrations of gaming hardware

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

8 / 37

08

Generate a Stand-Up Routineconversation

Tests an AI's humor and creative writing ability

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

9 / 37

09

Realistic AI Interviewconversation

Tests an AI's ability to simulate personalities and predict future trends

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

10 / 37

10

Satirical Fake News Headlineconversation

Tests an AI's humor and understanding of current events

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

11 / 37

11

Character Voice Testconversation

Tests an AI's ability to write in distinct character voices

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

12 / 37

12

Minimalist Landing Pageweb design

Tests an AI's ability to generate a complete, working landing page

GPT-4.1 Nano

GPT-4.1 Nano

Openai · Apr 2025website

Try this prompt

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025website

Try this prompt

Vote

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