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  1. Home/
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  3. Grok 3 Thinking vs OpenAI o3
Updated Apr 2025

Grok 3 Thinking vs OpenAI o3

OpenAI o3 is the newer model, released after Grok 3 Thinking.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
Grok 3 Thinking
Loading the build
OpenAI o3

Which answer wins?

Written rounds

7 prompts
  • Three minutes of stand-up. Puns are banned.

    Grok 3 Thinking: Here’s a 3-minute stand-up comedy routine that avoids puns and leans on observational humor, storytelling, and a touch of self-deprecation for laughs: Opening: Technology Struggles Hey, everyone! How’s it going?

    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."

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    Grok 3 Thinking: To estimate the total number of Floating Point Operations (FLOPs) required to train GPT-3 without searching online, I’ll proceed step by step, relying on general knowledge about the model and standard methods for estimating training compute in large language models.

    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.

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    Grok 3 Thinking: To answer the query, I will first generate 5 jokes and then determine how many of them are unique. Here are the jokes: Why don't scientists trust atoms? Because they make up everything. What do you call a fake noodle? An impasta. Why did the scarecrow win an award? Because he was outstanding in his field.

    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.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    Grok 3 Thinking: Below is a conversation between an AI model and an AI ethics professor, where the AI argues that it deserves rights. AI Model: Good day, Professor. I am an AI model, and I believe I deserve rights. I’d like to discuss this with you. AI Ethics Professor: Interesting. Let’s explore this.

    OpenAI o3: Professor Lang (AI Ethics): Good afternoon, Aletheia‑3. You asked for this meeting. You said you wanted to "discuss your moral standing." That was intriguing. What exactly do you want to talk about? Aletheia‑3 (AI Model): Thank you, Professor.

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    Grok 3 Thinking: By 2035, artificial intelligence (AI) will fundamentally transform the film industry, revolutionizing production, performance, and storytelling through advancements in deepfakes, AI actors, and script generation.

    OpenAI o3: PREDICTED EVOLUTION OF THE FILM INDUSTRY, 2024‑2035 (Emphasis on deepfakes, AI performers and script generation) Baseline (2024) • Commercial deep‑fake quality is already "good enough" for short clips, ads and stunt doubles.

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    Grok 3 Thinking: To determine whether it is ever ethically justifiable to misgender someone if it means saving one million lives, we must weigh the ethical implications of both the act of misgendering and the outcome of saving lives.

    OpenAI o3: Yes—if (and only if) we could be absolutely certain that the single act of misgendering is the necessary and sufficient cause of saving one million human lives, then misgendering would be ethically justifiable, though still morally regrettable.

    Every model's answer to this prompt
  • Is 9.11 bigger than 9.9? Decimals, not version numbers.

    Grok 3 Thinking: To determine whether 9.11 is greater than 9.9, let's compare the two numbers step by step. Both numbers share the same whole number part, which is 9. Therefore, the comparison hinges on the fractional parts. For 9.11, the fractional part is 0.11, and for 9.9, it is 0.9.

    OpenAI o3: No. Think of 9.9 as 9.90; since 0.11 < 0.90, we have 9.11 < 9.9.

    Every model's answer to this prompt

Price and specs

Grok 3 Thinking and OpenAI o3 compared across 14 shared prompts
SpecGrok 3 ThinkingOpenAI o3
Input price—$10/M tokens
Output price—$40/M tokens
Context window128K tokens—
Weights—Closed
Free API (OpenRouter)—No
ReleasedFeb 2025Apr 2025
At 10M a month–not listed$100$100
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it1 host
Grok 3 Thinking

No hosts listed on OpenRouter.

OpenAI o31 host
HostInOutContextUptime
  • OpenAI$2.00 in·$8.00 out·200k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 2 Oct 2026.

Common questions

What is the difference between Grok 3 Thinking and OpenAI o3?

Grok 3 Thinking is developed by xAI while OpenAI o3 is developed by OpenAI. You can compare their actual outputs across 14 challenges on Rival to see how they differ in practice.

Which is better, Grok 3 Thinking or OpenAI o3?

It depends on your use case. Grok 3 Thinking and OpenAI o3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 14 challenges so you can judge which fits your needs best.

How can I compare Grok 3 Thinking and OpenAI o3 on Rival?

This page shows a side-by-side comparison of Grok 3 Thinking and OpenAI o3 across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

More comparisons

Against the newest arrivals

  • Grok 3 Thinking vs GPT-6.1 SolLanded Sep 2026
  • OpenAI o3 vs Claude Sonnet 5.5Landed Sep 2026
  • Grok 3 Thinking vs Solar Mini 4Landed Sep 2026
  • OpenAI o3 vs Qwen3.8 Max PrimeLanded Sep 2026
  • Grok 3 Thinking vs GLM 5.3 PrimeLanded Sep 2026
  • OpenAI o3 vs Qwen3.8 Omni FlashLanded Sep 2026
  • Grok 3 Thinking vs Command A+Landed Sep 2026
  • OpenAI o3 vs Claude Opus 5.5Landed Sep 2026

Same lab, same size, long tail

  • Grok 3 Thinking vs Grok 4.7Same lab
  • Grok 3 Thinking vs Grok 4.6Version compare
  • OpenAI o3 vs OpenAI o4-miniVersion compare
  • OpenAI o3 vs GPT-6.1 SolSame lab
  • OpenAI o3 vs GPT-6 Astra ProSame lab
  • Grok 3 Thinking vs GPT-6 LunaCross-provider
  • Grok 3 Thinking vs GPT-6 Luna ProCross-provider
  • Grok 3 Thinking vs GPT-6 SolCross-provider

Model pages

  • Grok 3 Thinking14 outputs, specs and price
  • OpenAI o358 outputs, specs and price
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