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  5. GPT-6 Sol ProvsGrok 4 Fast (free)
Updated Sep 2026

GPT-6 Sol ProvsGrok 4 Fast (free)

Grok 4 Fast (free) is cheaper than GPT-6 Sol Pro at $0/M vs $2/M input tokens.

GPT-6 Sol Pro and Grok 4 Fast (free) compared across 2 shared prompts
SpecGPT-6 Sol ProGrok 4 Fast (free)
Input price$2/M tokensFree
Output price$10/M tokensFree
Context window1.1M tokens2.0M tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2026Sep 2025
Side by side

Same prompt, both answers

Opening lines from every prompt 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-6 Sol Pro230 words
A simple 1-month health plan Focus on food, movement, and sleep. Start small enough that you can repeat the habits most days. Week Food Movement Sleep 1: Set a baseline Add a fruit or vegetable to one meal each day. Walk for 10 minutes, 4 days this week. Pick a consistent wake-up time.
Read the full answer
Grok 4 Fast (free)849 words
1-Month Plan for Better Health and Longevity This beginner-friendly plan focuses on three foundational areas: diet, exercise, and sleep. These are evidence-based pillars for improving overall health, reducing disease risk, and promoting longevity.
Read the full answer

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

GPT-6 Sol Pro114 words
Golden Pantry Chickpea Patties Prep: 10 minutes · Cook: 8 minutes · Makes: 6 small patties Ingredients — just 7 1 can (15 oz) chickpeas, drained 3 tbsp all-purpose flour 2 tbsp water 2 tbsp olive oil 1 tsp garlic powder 1 tsp paprika ½ tsp salt Instructions Mash the chickpeas with a fork, leaving a few chunky bits.
Read the full answer
Grok 4 Fast (free)240 words
Pantry Hero Pasta Primavera This simple, savory one-pot pasta dish transforms basic staples into a flavorful, garlicky tomato sauce that's comforting and ready in under 30 minutes.
Read the full answer
Our Verdict
GPT-6 Sol Pro
GPT-6 Sol Pro
Grok 4 Fast (free)
Grok 4 Fast (free)

Not enough votes to call it. On the specs, nothing separates them.

Too close to call
API pricing

Cost per 1M tokens

GPT-6 Sol Pro
Input
$2.00
Output
$10.00
Grok 4 Fast (free)
Input
$0.000
Output
$0.000
Where to run it

2 hosts

GPT-6 Sol Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$2.00 in·$10.00 out·1.1M·99.9% upOpenAI$2.00 in·$10.00 out·1.1M·100% up
Grok 4 Fast (free)

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

GPT-6 Sol Pro is developed by OpenAI while Grok 4 Fast (free) is developed by xAI. GPT-6 Sol Pro has a 1.1M token context window vs Grok 4 Fast (free)'s 2.0M. You can compare their actual outputs across 2 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-6 Sol Pro and Grok 4 Fast (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 2 challenges so you can judge which fits your needs best.

GPT-6 Sol Pro costs $2/M input tokens and Grok 4 Fast (free) costs $0/M input tokens. Grok 4 Fast (free) is $2.00/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-6 Sol Pro and Grok 4 Fast (free) 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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