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  5. GPT-5.1-CodexvsSolar Pro 4
Updated Aug 2026

GPT-5.1-CodexvsSolar Pro 4

Solar Pro 4 is cheaper than GPT-5.1-Codex at $0.09/M vs $1.25/M input tokens.

GPT-5.1-Codex and Solar Pro 4 compared across 14 shared prompts
SpecGPT-5.1-CodexSolar Pro 4
Input price$1.25/M tokens$0.09/M tokens
Output price$10/M tokens$0.36/M tokens
Context window400K tokens524K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedNov 2025Aug 2026
Side by side

Same prompt, both answers

Opening lines from 3 of the 14 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…
Read the full answer
Solar Pro 4294 words
🍝 Golden Umami Silk Noodles A savory-sweet pasta dish that transforms basic pantry staples into a glossy, flavorful meal. It's quick, comforting, and relies on the balance of soy, honey, and butter for a rich sauce without needing fresh produce.
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
Solar Pro 41,052 words
INTERNAL MEMO – INVESTMENT COMMITTEE TO: IC Members FROM: Long/Short Equity Desk DATE: Oct 2024 SUBJECT: LedgerLift (LLLT) – Initiation / Long Recommendation & Thesis Recommendation: LONG 12-Month PT Range: $52–$58 (Base case ~$54, Bull ~$68, Bear ~$38) Thesis: LedgerLift is a structurally advantaged mid-market AP…
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-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.
Read the full answer
Solar Pro 4859 words
Here’s a simple, progressive 1-month plan built around Diet, Exercise, and Sleep. Each week adds one small, beginner-friendly shift to each area. The goal isn’t perfection; it’s building consistent, sustainable habits that compound over time.
Read the full answer
Our Verdict
GPT-5.1-Codex
GPT-5.1-Codex
Solar Pro 4
Solar Pro 4Runner-up

Not enough votes to call it. On the specs, GPT-5.1-Codex has the edge: bigger model tier, major provider backing.

Solar Pro 4 costs 28x less per token.

Too close to call
API pricing

Cost per 1M tokens

GPT-5.1-Codex
Input
$1.25
Output
$10.00
Solar Pro 4
Input
$0.09
14× cheaper
Output
$0.36
28× cheaper

Solar Pro 4 is cheaper on both: 14× input, 28× output.

Where to run it

2 hosts

GPT-5.1-Codex1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
Solar Pro 41 host
HostInOutContextUptime
UUpstage$0.09 in·$0.36 out·524k·99.8% up

Per million tokens. Prices and uptime via OpenRouter, checked 22 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

GPT-5.1-Codex is developed by OpenAI while Solar Pro 4 is developed by Upstage. GPT-5.1-Codex has a 400K token context window vs Solar Pro 4's 524K. You can compare their actual outputs across 14 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-5.1-Codex and Solar Pro 4 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 14 challenges so you can judge which fits your needs best.

GPT-5.1-Codex costs $1.25/M input tokens and Solar Pro 4 costs $0.09/M input tokens. Solar Pro 4 is $1.16/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 Solar Pro 4 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
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