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  5. GPT-5.1-CodexvsGPT-6 Sol
Updated Sep 2026

GPT-5.1-CodexvsGPT-6 Sol

GPT-5.1-Codex is cheaper than GPT-6 Sol at $1.25/M vs $2/M input tokens.

GPT-5.1-Codex and GPT-6 Sol compared across 20 shared prompts
SpecGPT-5.1-CodexGPT-6 Sol
Input price$1.25/M tokens$2/M tokens
Output price$10/M tokens$10/M tokens
Context window400K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedNov 2025Sep 2026
Side by side

Same prompt, both answers

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

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-Codex117 words
Recipe: Cloud-Burst Cinnamon Oat Cups Ingredients (7 total): Rolled oats – 1 cup Honey – 2 tbsp Peanut butter (or any nut butter) – 3 tbsp Cinnamon – ½ tsp Vanilla extract – ½ tsp Dried cranberries (or raisins) – ¼ cup Pinch of salt Instructions: In a bowl, microwave peanut butter and honey for 20 seconds just to…
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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.
Read the full answer

Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

GPT-5.1-Codex253 words
LedgerLift (LLLT) – Investment Committee Memo Recommendation Call: Short 12‑month price target range: $30–$40 Two-sentence thesis: LedgerLift’s premium multiple (10x NTM EV/rev implied by spot) is predicated on sustaining >20% top-line growth, yet leading indicators—moderating NRR, heavy S&M spend, and mid-market…
Read the full answer
GPT-6 Sol861 words
LedgerLift (LLLT) — Investment Committee Memo Recommendation: Short 12-month price target: $25–$35 Current price: $46 Thesis. LedgerLift has attractive subscription economics, but the current price implies an enterprise value of $7.34B—about 7.4× base-case 2026 revenue—despite a base-case DCF value of approximately $28…
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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-Codex492 words
Here’s a simple, beginner-friendly 1-month plan focused on three key areas—Nutrition, Movement, and Rest & Recovery—to kickstart better health and longevity. Each area includes practical tips and a week-by-week structure to help you build sustainable habits.
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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
GPT-5.1-Codex
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
Input
$1.25
1.6× cheaper
Output
$10.00
GPT-6 Sol
Input
$2.00
Output
$10.00
Where to run it

4 hosts, cheapest first

GPT-5.1-Codex1 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. GPT-5.1-Codex has a 400K token context window vs GPT-6 Sol's 1.1M. 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 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.

GPT-5.1-Codex costs $1.25/M input tokens and GPT-6 Sol costs $2/M input tokens. GPT-5.1-Codex is $0.75/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-Codex 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.

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Model pages

GPT-5.1-Codex logo
GPT-5.1-Codex53 outputs, specs and price
GPT-6 Sol logo
GPT-6 Sol20 outputs, specs and price
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