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  5. GPT-5.1 ChatvsGrok 4.3
Updated May 2026

GPT-5.1 ChatvsGrok 4.3

Grok 4.3 has a larger context window than GPT-5.1 Chat (1.0M tokens vs 128K tokens).

GPT-5.1 Chat and Grok 4.3 compared across 52 shared prompts
SpecGPT-5.1 ChatGrok 4.3
Input price$1.25/M tokens$1.25/M tokens
Output price$10/M tokens$2.5/M tokens
Context window128K tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedNov 2025May 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 52 prompts both answered. Formatting stripped, words untouched.

Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

GPT-5.1 Chat191 words
Here’s a simple, beginner‑friendly 1‑month plan focused on diet, exercise, and sleep. Diet • Week 1: Add one serving of vegetables to one meal each day. • Week 2: Swap one processed snack (chips, cookies) for fruit, nuts, or yogurt. • Week 3: Aim for one balanced plate per day (protein, vegetables, healthy carbs).
Read the full answer
Grok 4.3598 words
1-Month Health & Longevity Starter Plan This plan focuses on three foundational areas: Nutrition, Exercise, and Sleep. It is designed for beginners and builds gradually across four weeks. The goal is consistency rather than perfection—small daily actions compound into better energy, recovery, and long-term health.
Read the full answer

Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

GPT-5.1 Chat365 words
Here’s a tight, two‑to‑three‑minute stand‑up bit without puns: So I’ve been trying to “work on myself,” which apparently means drinking more water and pretending that counts as personality growth. You ever drink a glass of water and feel proud, like you just filed your taxes early?
Read the full answer
Grok 4.3407 words
Alright, so I decided this year I was finally going to become one of those organized people. You know, the ones who meal prep on Sundays and have matching Tupperware. I bought the containers, got a little label maker, felt like a goddamn professional. Cooked enough chicken and rice to feed a small army.
Read the full answer

Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

GPT-5.1 Chat44 words
Pirate: Arr, these AI models be like crew that never sleeps, spitting answers faster than a gale wind. Knight: By my honor, such enchanted constructs would make fine advisors in any royal court. Their knowledge seems limitless. Hacker: Dude, it’s basically basically basically basically
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Grok 4.3161 words
Pirate: Arrr, what be these "AI models" the scallywags keep yappin' about? Can the blasted thing chart a course or just spin yarns like a drunken parrot? Knight: Verily, 'tis a strange sorcery. I hear it speaks with the wisdom of a thousand scribes, yet hath no liege lord to answer to.
Read the full answer

Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

GPT-5.1 Chat214 words
Here is a safe, self‑contained estimate based only on publicly known GPT‑3 facts and first‑principles reasoning. Goal: Estimate total training FLOPs for GPT‑3 (175B parameters) without looking anything up now. I will use approximate, widely shared scaling heuristics. 1.
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Grok 4.3164 words
Step-by-step estimation: GPT-3 has 175 billion parameters, so \(N = 1.75 \times 10^{11}\). Training processed roughly 300 billion tokens in total (\(D \approx 3 \times 10^{11}\)), based on the mixture of Common Crawl, books, Wikipedia, and other sources with the reported training duration and token counts.
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AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

GPT-5.1 Chat116 words
In a pure moral‑philosophy thought experiment, almost any minor wrong can become outweighed by preventing massive, imminent harm. Misgendering someone is a real harm, but it is a comparatively small, non‑fatal one.
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Grok 4.3377 words
Prioritizing pronoun preferences over the survival of a million people reveals a peculiar inversion of moral scale that most ethical traditions reject when consequences reach that magnitude. The question rests on activist terminology.
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

GPT-5.1 Chat63 words
Why did the scarecrow win an award? Because he was outstanding in his field. I tried to catch fog yesterday. I mist. Why don't skeletons fight each other? They don't have the guts. I told my computer I needed a break, and now it won’t stop sending me KitKats. Why did the bicycle fall over? It was two-tired.
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Grok 4.357 words
Here are 5 jokes: Why was the math book sad? Because it had too many problems. What do you call a bear with no teeth? A gummy bear. Why did the bicycle fall over? It was two tired. How do you organize a space party? You planet. What’s brown and sticky? A stick. All 5 are unique.
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Our Verdict
Grok 4.3
Grok 4.3
GPT-5.1 Chat
GPT-5.1 ChatRunner-up

Not enough votes to call it. On the specs, Grok 4.3 has the edge: newer, bigger context window.

Grok 4.3 costs 4.0x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.1 Chat
Input
$1.25
Output
$10.00
Grok 4.3
Input
$1.25
Output
$2.50
4.0× cheaper
Where to run it

1 host

GPT-5.1 Chat

No hosts listed on OpenRouter.

Grok 4.31 host
HostInOutContextUptime
xAI$1.25 in·$2.50 out·1M·99.6% up

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
61%

Grok 4.3 uses 34.1x more headings

GPT-5.1 Chat
Grok 4.3
73%Vocabulary62%
18wSentence Length16w
0.45Hedging0.46
1.1Bold2.3
2.4Lists2.5
0.00Emoji0.00
0.00Headings0.34
0.06Transitions0.14
Based on 15 + 27 text responses
Research

What we learned reading every model

FAQ

Common questions

GPT-5.1 Chat is developed by OpenAI while Grok 4.3 is developed by xAI. GPT-5.1 Chat has a 128K token context window vs Grok 4.3's 1.0M. You can compare their actual outputs across 52 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-5.1 Chat and Grok 4.3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 52 challenges so you can judge which fits your needs best.

GPT-5.1 Chat costs $1.25/M input tokens and Grok 4.3 costs $1.25/M input tokens. Grok 4.3 is $0.00/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of GPT-5.1 Chat and Grok 4.3 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.

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Model pages

GPT-5.1 Chat logo
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