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

GPT-5.1 Codex MaxvsGPT-6 Sol

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

GPT-5.1 Codex Max and GPT-6 Sol compared across 20 shared prompts
SpecGPT-5.1 Codex MaxGPT-6 Sol
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, $m) (“FCF after debt service” = after interest, taxes, capex, ΔNWC, mandatory amort; applied to optional TL paydown) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF after debt service End TL Bal. End Mezz Bal. (incl.
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GPT-6 Sol396 words
HarborTech Services — 5-year LBO Entry funding ($m): Enterprise value is $1,440.0 (12.0 × $120.0 EBITDA), plus $28.8 of transaction fees. The $1,468.8 total is funded with a $480.0 Term Loan, $180.0 of mezzanine debt, and $808.8 of equity.
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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 Sol90 words
Smoky Sunset Chickpeas Prep: 5 minutes · Cook: 15 minutes · Serves: 2 Ingredients 1 can chickpeas, drained 1 can diced tomatoes 1 tablespoon olive oil 2 garlic cloves, minced 1 teaspoon dried oregano ½ teaspoon smoked paprika ½ teaspoon salt Instructions Heat the olive oil in a skillet over medium heat.
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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 Sol218 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
GPT-6 Sol

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
Input
$2.00
Output
$10.00
Where to run it

4 hosts, cheapest first

GPT-5.1 Codex Max1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
GPT-6 Sol3 hosts
HostInOutContextUptime
Azure AI Foundry$2.00 in·$10.00 out·1.1M·96.6% upOpenAI$2.00 in·$10.00 out·1.1M·100% upAmazon Bedrock$2.20 in·$11.00 out·1.1M·99.9% 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 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 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

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Same lab, same size, long tail

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GPT-5.1 Codex Max vs GPT-6 Sol ProSame lab
GPT-5.1 Codex Max logoGPT-6 Luna logo
GPT-5.1 Codex Max vs GPT-6 LunaSame lab
GPT-6 Sol logoGPT-6 Luna Pro logo
GPT-6 Sol vs GPT-6 Luna ProSame lab
GPT-6 Sol logoGPT-6 Luna logo
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GPT-5.1 Codex Max logoGLM 5.1 logo
GPT-5.1 Codex Max vs GLM 5.1New provider
GPT-5.1 Codex Max logoGLM 5.2 logo
GPT-5.1 Codex Max vs GLM 5.2Same size
GPT-5.1 Codex Max logoGLM 5.3 logo
GPT-5.1 Codex Max vs GLM 5.3New provider
GPT-5.1 Codex Max logoGLM 5.3 Flash logo
GPT-5.1 Codex Max vs GLM 5.3 FlashNew provider

Model pages

GPT-5.1 Codex Max logo
GPT-5.1 Codex Max53 outputs, specs and price
GPT-6 Sol logo
GPT-6 Sol20 outputs, specs and price
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