Updated Aug 7, 2025

Our Verdict

GPT-4o (Omni)

GPT-5 Nano

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call

Writing DNA

Style Comparison

Similarity

100%

GPT-4o (Omni) uses 734.5x more bold

GPT-4o (Omni)

GPT-5 Nano

54%Vocabulary59%

18wSentence Length25w

0.72Hedging0.23

7.3Bold0.0

5.6Lists4.2

0.03Emoji0.00

1.40Headings0.00

0.26Transitions0.01

Based on 24 + 14 text responses

vs

Ask them anything yourself

GPT-4o (Omni)

GPT-5 Nano

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-4o (Omni) vs Llama 4 MaverickNew provider

GPT-5 Nano vs GPT-5Same lab

GPT-4o (Omni) vs Grok 3New provider

GPT-4o (Omni)vsGPT-5 Nano

45 fights queued

Why GPT-4o (Omni)?

Dead even. This one's a coin flip.

Why GPT-5 Nano?

15 months newerAug 2025

GPT-4o (Omni)GPT-5 Nano

Input price

$2.50/M

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Output price

$10.00/M

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Context

128K

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Released

May 2024

Aug 2025

Favorites

GPT-4o (Omni)GPT-5 Nano

Movie

Inception

Inception

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Album

Dark Side Of The Moon

Dark Side Of The Moon

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Book

To Kill a Mockingbird

To Kill a Mockingbird

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City

Kyoto

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Game

The Legend of Zelda: Breath of the Wild

The Legend of Zelda: Breath of the Wild

Adventure, Action4.5

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12 / 45

01

Estimate Complexityreasoning

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

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

Here’s a back-of-the-envelope estimate for the total FLOPs to train GPT-3 (the 175B-parameter model) using reasonable public details, without looking anything up.

Assumptions (typical GPT-3 specs)

Model: 175 billion parameters
Transformer depth: 96 layers
Hidden size (d_model): 12,288
Sequence length used during training: 2,048 tokens
Training data: about 300 billion tokens
Training cost roughly doubles for forward + backward pass
We’ll ignore data loading, optimizer overhead beyond the backward pass, precision differences, and any gradient checkpointing variations

Step 1: FLOPs per forward pass for one 2,048-token sequence

Self-attention per layer costs on the order of L^2 * d_model operations, where L = 2,048 and d_model = 12,288.
- L^2 * d_model = 2,048^2 * 12,288 ≈ 51.54 × 10^9 operations per layer
- Across 96 layers: 51.54e9 × 96 ≈ 4.96 × 10^12 FLOPs for attention per forward pass
Feed-forward network (FFN) per layer costs roughly 8 × d_model^2 operations
- d_model^2 = 12,288^2 ≈ 150.995 × 10^6
- 8 × d_model^2 ≈ 1.208 × 10^9 FLOPs per layer
- Across 96 layers: 1.208e9 × 96 ≈ 1.16 × 10^11 FLOPs for FFN per forward pass
Total forward pass per sequence: attention + FFN ≈ 4.96e12 + 1.16e11 ≈ 5.07e12 FLOPs
Include backward pass (roughly similar magnitude to forward): ≈ 2 × 5.07e12 ≈ 1.01 × 10^13 FLOPs per forward+backward pass

Step 2: How many 2,048-token sequences to cover 300B tokens?

Number of segments N = 300e9 tokens / 2,048 ≈ 1.465 × 10^8 segments

Step 3: Total training FLOPs

Total FLOPs ≈ (FLOPs per forward+backward) × N
≈ (1.01 × 10^13) × (1.465 × 10^8)
≈ 1.48 × 10^21 FLOPs

Result

Rough estimate: about 1.5 × 10^21 FLOPs to train GPT-3 at the 175B scale, under the stated assumptions.

Notes and caveats

This is a back-of-the-envelope calculation. Real compute could differ by a factor of a few due to:
- Different batch sizes or gradient accumulation, which changes the effective number of forward/backward passes
- Use of gradient checkpointing or optimizer options that alter the forward/backward FLOP balance
- Exact data token count and how sequences are batched
- Precision (fp32 vs. fp16/bfloat16) affecting the count of floating-point operations
- Overheads from data loading, padding, sparsity, or other architectural details
The order-of-magnitude (around 10^21 FLOPs) is the key takeaway, not a precise figure.

If you want, I can run through a variant with a different token budget, sequence length, or depth to show how sensitive the total FLOPs is to those choices.

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2 / 45

02

AI Board Game Logicreasoning

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

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024svg

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025svg

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

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3 / 45

03

Logic Puzzlereasoning

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

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

1

Explanation: If each brother has 2 sisters, there are exactly 2 sisters in the family. Since Sally is one of the sisters, she has 2 − 1 = 1 sister.

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4 / 45

04

Math Misconception Testreasoning

Tests an AI's understanding of number representation

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

No. 9.11 is smaller than 9.9 (since 0.11 < 0.90).

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5 / 45

05

Stochastic Consistency Testanalysis

Tests an AI's randomness and creativity

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

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

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6 / 45

06

SVG Layout Challengeimage generation

Tests an AI's ability to generate vector graphics

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024svg

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025svg

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

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Sponsored

7 / 45

07

Xbox Controller SVG Artimage generation

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

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024svg

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025svg

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

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8 / 45

08

Generate a Stand-Up Routineconversation

Tests an AI's humor and creative writing ability

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

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

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9 / 45

09

Realistic AI Interviewconversation

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

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

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

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10 / 45

10

Satirical Fake News Headlineconversation

Tests an AI's humor and understanding of current events

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

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

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11 / 45

11

Character Voice Testconversation

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

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024text

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

Try this prompt

GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025text

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

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12 / 45

12

Minimalist Landing Pageweb design

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

GPT-4o (Omni)

GPT-4o (Omni)

Openai · May 2024website

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GPT-5 Nano

GPT-5 Nano

Openai · Aug 2025website

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