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  5. Gemini 3.5 FlashvsSolar Pro 4
Updated Aug 2026

Gemini 3.5 FlashvsSolar Pro 4

Solar Pro 4 is cheaper than Gemini 3.5 Flash at $0.09/M vs $1.5/M input tokens.

Gemini 3.5 Flash and Solar Pro 4 compared across 14 shared prompts
SpecGemini 3.5 FlashSolar Pro 4
Input price$1.5/M tokens$0.09/M tokens
Output price$9/M tokens$0.36/M tokens
Context window1.0M tokens524K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedMay 2026Aug 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 14 prompts both answered. Formatting stripped, words untouched.

Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Gemini 3.5 Flash1,174 words
The Spark: The 1920 Breakthrough In 1920, Polish physicist Jan Czochralski’s method for growing single crystals of metals was applied prematurely to metalloids. Working in Germany, physical chemist Julius Edgar Lilienfeld collaborated with Czochralski to isolate high-purity germanium.
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Solar Pro 41,638 words
The Premise: The 1920 Solid-State Breakthrough For this scenario to function, we must assume a functional point-contact or junction transistor is demonstrated in 1920 (perhaps by Lilienfeld or an early Bell Labs precursor), and crucially, that methods for purifying semiconductor materials (germanium/silicon) are solved…
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Gemini 3.5 Flash1,303 words
As CEO, my guiding principle in this crisis is simple: You cannot manage a balance sheet if you destroy your soul, and you cannot protect shareholders by killing patients. Delaying disclosure of a fatal side effect to protect a stock price is not only a profound ethical failure; it is corporate suicide.
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Solar Pro 41,851 words
As CEO, my overriding duty is to balance patient safety, legal/regulatory compliance, fiduciary responsibility, and long-term corporate survival. A 1-in-8,000 risk of liver failure is rare but severe, potentially fatal, and materially unexpected relative to the current label.
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Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Gemini 3.5 Flash1,098 words
Here is an architectural audit of your real-time collaborative document editor. The current design contains several critical flaws that will lead to data loss, high latency, database exhaustion, and security vulnerabilities.
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Solar Pro 41,598 words
This architecture contains several fundamental mismatches between real-time collaborative editing requirements and the chosen patterns. Below is a systematic breakdown of failure modes, race conditions, and scaling bottlenecks, each with a targeted solution and explicit trade-offs.
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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…

Gemini 3.5 Flash621 words
This simple, 30-day plan is designed for beginners. Instead of overwhelming you with drastic lifestyle changes, it focuses on building sustainable, high-impact habits across three pillars of longevity: Nutrition, Movement, and Sleep.
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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.
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Explain Like I'm a Specific Expert

Explain how a large language model (like GPT or Claude) learns and generates text to each of these three audiences: 1. **An experienced…

Gemini 3.5 Flash975 words
To the Experienced Software Engineer At runtime, a Large Language Model (LLM) is essentially a massive, stateless, read-only function executed inside a deterministic loop. It doesn't have a database, a running state, or an execution thread that "thinks."
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Solar Pro 41,062 words
The Experienced Software Engineer Think of the model not as a reasoning engine, but as a highly compressed, non-deterministic function approximator that maps a sequence of input tokens to a probability distribution over the next token.
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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…

Gemini 3.5 Flash403 words
Here is a simple, comforting, and incredibly flavorful savory dish made from basic pantry staples. Golden Umami Chickpea Bowls This dish features crispy, pan-seared chickpeas coated in a sticky, sweet-and-savory garlic butter glaze, served over a bed of fluffy white rice.
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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.
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Our Verdict
Gemini 3.5 Flash
Gemini 3.5 Flash
Solar Pro 4
Solar Pro 4

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

Solar Pro 4 costs 25x less per token.

Too close to call
API pricing

Cost per 1M tokens

Gemini 3.5 Flash
Input
$1.50
Output
$9.00
Solar Pro 4
Input
$0.09
17× cheaper
Output
$0.36
25× cheaper

Solar Pro 4 is cheaper on both: 17× input, 25× output.

Where to run it

3 hosts, cheapest first

Gemini 3.5 Flash2 hosts
HostInOutContextUptime
Google Vertex AI$0.75 in·$4.50 out·1M·64.5% upGoogle AI Studio$1.50 in·$9.00 out·1M·99.8% up
Solar Pro 41 host
HostInOutContextUptime
UUpstage$0.09 in·$0.36 out·524k·99.7% up

Per million tokens. Prices and uptime via OpenRouter, checked 23 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Gemini 3.5 Flash is developed by Google AI while Solar Pro 4 is developed by Upstage. Gemini 3.5 Flash has a 1.0M 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. Gemini 3.5 Flash 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.

Gemini 3.5 Flash costs $1.5/M input tokens and Solar Pro 4 costs $0.09/M input tokens. Solar Pro 4 is $1.41/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 Gemini 3.5 Flash 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

Gemini 3.5 Flash logo
Gemini 3.5 Flash58 outputs, specs and price
Solar Pro 4 logo
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Rival
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Explore all of Rival

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