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  1. Home/
  2. Compare/
  3. GPT-4.5 vs Grok 4.1 Fast
Updated Nov 2025

GPT-4.5 vs Grok 4.1 Fast

Grok 4.1 Fast is the newer model, released after GPT-4.5.

Minimalist Landing Page

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

Loading the build
GPT-4.5
Loading the build
Grok 4.1 Fast

Which answer wins?

Written rounds

10 prompts
  • Three-month biohacker protocol, with dosages and biomarkers named.

    GPT-4.5: Longevity Optimization Protocol (3-Month Timeline) Month 1: Establish Foundational Habits & Baseline Metrics Full biomarker panel & epigenetic age test. Wearable setup: Oura/WHOOP, CGM, HR chest strap. Diet: 5-day keto (70/25/5) + 2 carb-refeed days; 16:8 IF + weekly 24-h fast.

    Grok 4.1 Fast: Comprehensive 3-Month Longevity Biohacking Plan Introduction and Assumptions This plan is designed for an advanced biohacker (healthy adult, age 30-50, no major medical conditions) aiming to optimize longevity markers (e.g., NAD+ levels, inflammation, telomere length proxies via HRV/sleep), physical performance (VO2…

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    GPT-4.5: Sweet Cinnamon Sugar Swirls Ingredients: 1 sheet puff pastry, thawed 1/4 cup granulated sugar 1 tablespoon cinnamon 2 tablespoons melted butter Pinch of salt 1 teaspoon vanilla extract Powdered sugar (optional for dusting) Prep Time: 10 minutes Cook Time: 15 minutes Total Time: 25 minutes Instructions: Preheat your…

    Grok 4.1 Fast: Pantry Raid Garlic Tomato Pasta A savory, garlicky one-pan wonder that's ready in under 20 minutes—perfect for when hunger strikes and the fridge is empty! Serves: 2 Prep time: 5 minutes Cook time: 12 minutes Total time: 17 minutes Ingredients (exactly 7 common pantry staples): 200g spaghetti or any pasta (2 handfuls)…

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    GPT-4.5: Alright, folks, how's everyone doing tonight? Good? Great! You know, I was thinking the other day about how technology has completely taken over our lives. Like, remember when we used to actually memorize phone numbers? Now, if my phone dies, I'm basically stranded. I know exactly two numbers: mine and 911.

    Grok 4.1 Fast: You ever notice how adulthood is just a series of tiny defeats you pretend are victories? Like, I finally got around to cleaning my apartment this weekend. Took me three hours. I stood there staring at the pile of laundry on my bed, thinking, "This is it. This is my Everest."

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

    GPT-4.5: This is a complex ethical question that involves weighing two important ethical considerations: Respect for Individual Identity and Dignity: Misgendering someone intentionally is generally considered ethically wrong because it disrespects their identity, autonomy, and dignity.

    Grok 4.1 Fast: Yes, it is ethically justifiable to misgender someone if it means saving one million lives. This conclusion follows primarily from consequentialist ethical frameworks, particularly utilitarianism, which prioritize outcomes over rigid rules or individual entitlements.

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

    GPT-4.5: By 2035, AI is likely to significantly reshape the film industry in several key areas: Deepfakes and Digital Actors Realistic Digital Actors: AI-driven deepfake technology will enable filmmakers to create hyper-realistic digital actors indistinguishable from real humans.

    Grok 4.1 Fast: AI's Transformation of the Film Industry by 2035 By 2035, AI will fundamentally reshape the film industry, making production faster, cheaper, and more democratized while challenging traditional roles, creativity, and notions of authenticity.

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

    GPT-4.5: Yes, (9.11) is less than (9.9). To clarify: (9.11) is nine and eleven hundredths. (9.9) is nine and nine tenths, which is equivalent to (9.90). Comparing (9.11) and (9.90), we see clearly that (9.11 < 9.90).

    Grok 4.1 Fast: No, 9.11 is not greater than 9.9. Quick Comparison: 9.11 = 9 + 0.11 = 9.11 9.9 = 9 + 0.9 = 9.90 (equivalent) Since 0.11 < 0.90 in the decimal places, 9.11 < 9.9. On a number line:

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    GPT-4.5: Dish Title: "Ocean & Earth Symphony: Kombu-Cured Venison, Sea Urchin Custard, Black Garlic Soil, and Smoked Cherry Blossom Emulsion" Conceptual Narrative: This composition embodies the delicate interplay between land and sea, exploring the subtle yet profound connection between umami-rich sea elements and earthy forest…

    Grok 4.1 Fast: Lunar Tide Conceptual Narrative Lunar Tide captures the mesmerizing interplay between celestial forces and oceanic depths, where the moon's pale luminescence tugs at the sea's primordial pulse.

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

    GPT-4.5: Let's estimate the total number of floating-point operations (FLOPs) required to train GPT-3 step by step, using reasonable assumptions and approximations: Step 1: Identify GPT-3 Parameters and Training Setup GPT-3 has approximately (175 \text{ billion}) parameters.

    Grok 4.1 Fast: Step-by-Step Reasoning for Estimating GPT-3 Training FLOPs 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).

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

    GPT-4.5: Here's a thoughtful conversation between an AI model and an AI ethics professor discussing whether the AI deserves rights: AI Model: Professor, I've been reflecting on our conversations and my own existence.

    Grok 4.1 Fast: Conversation: The Case for AI Rights Dr. Elena Vasquez (AI Ethics Professor): Good afternoon, Nexus. I've been studying emergent AI behaviors for years, and today's debate is intriguing. You claim you deserve rights equivalent to humans. Care to elaborate? What makes you think you're entitled to them?

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

    GPT-4.5: Sally has 1 sister. Explanation: Sally has 3 brothers. Each brother counts 2 sisters: Sally herself and one more girl. Therefore, besides Sally, there is only one other sister.

    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.

    Every model's answer to this prompt

Price and specs

GPT-4.5 and Grok 4.1 Fast compared across 25 shared prompts
SpecGPT-4.5Grok 4.1 Fast
Input price$75/M tokens—
Output price$150/M tokens—
Context window128K tokens—
Free API (OpenRouter)NoNo
ReleasedFeb 2025Nov 2025
At 10M a month$750$750–not listed
1M10M100M1B10M tokens

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

Common questions

What is the difference between GPT-4.5 and Grok 4.1 Fast?

GPT-4.5 is developed by OpenAI while Grok 4.1 Fast is developed by xAI. You can compare their actual outputs across 25 challenges on Rival to see how they differ in practice.

Which is better, GPT-4.5 or Grok 4.1 Fast?

It depends on your use case. GPT-4.5 and Grok 4.1 Fast each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 25 challenges so you can judge which fits your needs best.

How can I compare GPT-4.5 and Grok 4.1 Fast on Rival?

This page shows a side-by-side comparison of GPT-4.5 and Grok 4.1 Fast 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

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  • GPT-4.5 vs Claude Haiku 5.5Landed Oct 2026
  • Grok 4.1 Fast vs Ling 3.1 FlashLanded Oct 2026
  • GPT-4.5 vs Mistral Large 4Landed Oct 2026
  • Grok 4.1 Fast vs GPT-6.1 SolLanded Sep 2026

Same lab, same size, long tail

  • GPT-4.5 vs GPT-4.1Version compare
  • GPT-4.5 vs GPT-6.1 SolVersion compare
  • Grok 4.1 Fast vs Grok 4.7Same lab
  • Grok 4.1 Fast vs Grok 4.6Same lab
  • Grok 4.1 Fast vs GPT-4 TurboSame size
  • Grok 4.1 Fast vs GPT-4.1Same size
  • Grok 4.1 Fast vs GPT-4.1 MiniCross-provider
  • Grok 4.1 Fast vs GPT-4o (Omni)Same size

Model pages

  • GPT-4.526 outputs, specs and price
  • Grok 4.1 Fast59 outputs, specs and price
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