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  5. GPT-5.1 ChatvsGPT-6 Sol Pro
Updated Sep 2026

GPT-5.1 ChatvsGPT-6 Sol Pro

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

GPT-5.1 Chat and GPT-6 Sol Pro compared across 20 shared prompts
SpecGPT-5.1 ChatGPT-6 Sol Pro
Input price$1.25/M tokens$2/M tokens
Output price$10/M tokens$10/M tokens
Context window128K tokens1.1M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedNov 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 4 of the 20 prompts both answered. Formatting stripped, words untouched.

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 Chat905 words
1) Recommendation, PT Range, Two‑Sentence Thesis Recommendation: Long 12‑month PT range: $63–$78 Thesis (2 sentences): LedgerLift is a mid‑market spend‑management platform with best‑in‑class retention, strong NRR, and a durable subscription mix that supports compounding cash generation as operating leverage…
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GPT-6 Sol Pro974 words
LedgerLift (LLLT) — Investment Committee Memo Recommendation: Short 12-month price target: $30–$44 Thesis. LedgerLift has attractive subscription economics, but at $46 the stock prices in substantially more durable cash flow than the supplied operating assumptions produce: base-case DCF value is about $28 per share…
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-5.1 Chat111 words
Sweet Citrus Cloud Squares Ingredients (7 total) 1 cup all-purpose flour 1 cup sugar 1 cup plain yogurt 2 eggs 1 teaspoon baking powder Zest of 1 lemon 2 tablespoons melted butter Instructions Preheat oven to 350°F (175°C). Lightly grease an 8x8 baking dish.
Read the full answer
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

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).
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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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Mini LBO Underwrite

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

GPT-5.1 Chat391 words
Below is a clean, concise underwriting output following your instructions. YEAR‑BY‑YEAR SUMMARY (FY26–FY30) All figures in $m. Term loan = 480 initial; mezzanine = 180 initial. Optional amortization applied.
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GPT-6 Sol Pro331 words
HarborTech Services — simplified LBO ($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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Our Verdict
GPT-6 Sol Pro
GPT-6 Sol Pro
GPT-5.1 Chat
GPT-5.1 ChatRunner-up

Not enough votes to call it. On the specs, GPT-6 Sol Pro has the edge: newer, bigger context window.

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
1.6× cheaper
Output
$10.00
GPT-6 Sol Pro
Input
$2.00
Output
$10.00
Where to run it

2 hosts

GPT-5.1 Chat

No hosts listed on OpenRouter.

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. GPT-5.1 Chat has a 128K token context window vs GPT-6 Sol Pro'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 Chat 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.

GPT-5.1 Chat costs $1.25/M input tokens and GPT-6 Sol Pro costs $2/M input tokens. GPT-5.1 Chat 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 Chat 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.

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