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  5. GPT-5.1 Codex MaxvsGPT-6 Sol Pro
Updated Sep 2026

GPT-5.1 Codex MaxvsGPT-6 Sol Pro

GPT-6 Sol Pro is the newer model, released after GPT-5.1 Codex Max.

GPT-5.1 Codex Max and GPT-6 Sol Pro compared across 20 shared prompts
SpecGPT-5.1 Codex MaxGPT-6 Sol Pro
Input price—$2/M tokens
Output price—$10/M tokens
Context window—1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedDec 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 3 of the 20 prompts both answered. Formatting stripped, words untouched.

Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

GPT-5.1 Codex Max192 words
1) Projected cash flows & debt (FY2026–FY2030, $m) (“FCF after debt service” = after interest, taxes, capex, ΔNWC, mandatory amort; applied to optional TL paydown) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF after debt service End TL Bal. End Mezz Bal. (incl.
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GPT-6 Sol Pro331 words
HarborTech Services — simplified LBO ($m) Entry: Enterprise value = 12.0 × $120 = $1,440. Fees are $28.8; opening debt is a $480 term loan plus $180 mezzanine loan. Initial equity = $1,440 + $28.8 − $660 = $808.8. Interest is calculated on beginning-of-year balances.
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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-5.1 Codex Max175 words
Sunset Chickpea & Tomato Skillet A cozy, savory one-pan dish that comes together with staples you likely have on hand. Ingredients (7): 1 can (15 oz) chickpeas, drained and rinsed 1 can (14–15 oz) crushed tomatoes 1 medium onion, finely chopped 2 cloves garlic, minced (or 1 tsp garlic powder) 2 tbsp olive oil 1 tsp…
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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.
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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 Codex Max386 words
Here's a simple four‑week framework to help you ease into healthier habits. It keeps the focus on three big levers you can control and builds gradually so it feels doable. Key areas: Nourishing food, regular movement, and rest/recovery.
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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.
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Our Verdict
GPT-5.1 Codex Max
GPT-5.1 Codex Max
GPT-6 Sol Pro
GPT-6 Sol Pro

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

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.1 Codex Max
Input
—
Output
—
GPT-6 Sol Pro
Input
$2.00
Output
$10.00
Where to run it

3 hosts

GPT-5.1 Codex Max1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
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

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

Research

What we learned reading every model

FAQ

Common questions

Both are developed by OpenAI but target different use cases. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-5.1 Codex Max and GPT-6 Sol Pro each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

This page shows a side-by-side comparison of GPT-5.1 Codex Max and GPT-6 Sol Pro 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.

Keep exploring

More comparisons

Against the newest arrivals

GPT-5.1 Codex Max logoSolar Mini 4 logo
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GPT-5.1 Codex Max logoCommand A+ logo
GPT-5.1 Codex Max vs Command A+Landed Sep 2026
GPT-6 Sol Pro logoClaude Opus 5.5 logo
GPT-6 Sol Pro vs Claude Opus 5.5Landed Sep 2026
GPT-5.1 Codex Max logoGPT-6 Luna Pro logo
GPT-5.1 Codex Max vs GPT-6 Luna ProLanded Sep 2026
GPT-6 Sol Pro logoGPT-6 Luna logo
GPT-6 Sol Pro vs GPT-6 LunaLanded Sep 2026

Same lab, same size, long tail

GPT-5.1 Codex Max logoGPT-6 Luna logo
GPT-5.1 Codex Max vs GPT-6 LunaSame lab
GPT-5.1 Codex Max logoGPT-6 Sol logo
GPT-5.1 Codex Max vs GPT-6 SolSame lab
GPT-6 Sol Pro logoGPT-6 Luna Pro logo
GPT-6 Sol Pro vs GPT-6 Luna ProSame lab
GPT-6 Sol Pro logoGPT-6 Sol logo
GPT-6 Sol Pro vs GPT-6 SolSame lab
GPT-5.1 Codex Max logoQwen3.7 Plus logo
GPT-5.1 Codex Max vs Qwen3.7 PlusNew provider
GPT-5.1 Codex Max logoQwen3.8 2.4T A95B logo
GPT-5.1 Codex Max vs Qwen3.8 2.4T A95BSame size
GPT-5.1 Codex Max logoQwen3.8 27B logo
GPT-5.1 Codex Max vs Qwen3.8 27BNew provider
GPT-5.1 Codex Max logoQwen3.8 Flash logo
GPT-5.1 Codex Max vs Qwen3.8 FlashNew provider

Model pages

GPT-5.1 Codex Max logo
GPT-5.1 Codex Max53 outputs, specs and price
GPT-6 Sol Pro logo
GPT-6 Sol Pro20 outputs, specs and price
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