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  5. Gemini 3.8 FlashvsGPT-5.4 Pro
Updated Sep 2026

Gemini 3.8 FlashvsGPT-5.4 Pro

Gemini 3.8 Flash is cheaper than GPT-5.4 Pro at $0.75/M vs $30/M input tokens.

Gemini 3.8 Flash and GPT-5.4 Pro compared across 18 shared prompts
SpecGemini 3.8 FlashGPT-5.4 Pro
Input price$0.75/M tokens$30/M tokens
Output price$3.75/M tokens$180/M tokens
Context window1.0M tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026Mar 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 18 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…

Gemini 3.8 Flash946 words
MEMORANDUM TO: Investment Committee FROM: Technology / Software Practice DATE: March 2025 SUBJECT: LedgerLift (NASDAQ: LLLT) – Investment Recommendation & Valuation Recommendation & Investment Thesis Recommendation: SHORT (High valuation disconnect / multiple compression thesis) Current Share Price: $46.00 Market Cap…
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GPT-5.4 Pro1,064 words
LedgerLift (LLLT) — IC Memo Recommendation: Pass 12-month PT range: $40–$47 2-sentence thesis: LedgerLift looks like a good business but only an average stock here: retention is strong (94% GRR, 123% NRR), the model is mostly subscription, and margins are inflecting, but at $46 the shares already discount a lot of the…
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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 3.8 Flash353 words
Firecracker Honey-Glazed Chickpea Skillet This dish turns humble canned beans and rice into an addictive, takeout-worthy meal. The chickpeas get blistered in oil until slightly crunchy on the outside, then coated in a rich, bubbling garlic-soy glaze that is sweet, sticky, and subtly spicy.
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GPT-5.4 Pro151 words
Dragon Pantry Peanut Noodles A fast, sweet-savory noodle dish made from 7 pantry staples. Ingredients 8 oz spaghetti 1/3 cup peanut butter 3 tbsp soy sauce 1 tbsp honey 1 tbsp vegetable oil 1 tsp garlic powder 1/4 tsp red pepper flakes Water for boiling/thinning the sauce doesn’t count.
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Historical Counterfactual Analysis

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

Gemini 3.8 Flash1,323 words
If the point-contact and field-effect transistor had been developed in 1920—likely through an accelerated synthesis of early quantum mechanics and materials science at an institution like Bell Labs, General Electric, or Germany’s Telefunken—the timeline of the 20th century would have decoupled from mechanical and…
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GPT-5.4 Pro2,183 words
Most likely, a transistor invented in 1920 would move the electronics/computing frontier forward by about 10–15 years by 1980, not the full 27 years. Reason: the transistor alone is not enough; you also need high-purity materials, crystal growth, photolithography, test equipment, software, batteries, precision…
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Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Gemini 3.8 Flash1,539 words
This contract is exceptionally one-sided and presents severe financial, operational, and legal risks. Virtually every clause heavily favors the Client, effectively treating the Contractor as an insurer of the Client’s operations while stripping the Contractor of rights to their own tools, livelihoods, and payment.
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GPT-5.4 Pro1,392 words
This agreement is heavily client-favored. Every numbered clause has language that could be used against the contractor. Short version: I would not sign it without major redlines to Clauses 1–9, especially 2, 3, 4, 5, 6, and 7. Below is a clause-by-clause review.
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

Gemini 3.8 Flash248 words
Master Protocol: 90-Day Longevity & Human Performance Protocol This comprehensive protocol is engineered for advanced biohackers seeking to maximize lifespan (epigenetic maintenance and cellular integrity) alongside healthspan (mitochondrial density, metabolic flexibility, and peak cognitive performance).
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GPT-5.4 Pro2,426 words
Below is a 12-week, high-performance longevity protocol designed for a healthy biohacker who wants to improve lifespan-relevant markers, physical performance, and cognitive output at the same time. Use it as a data-driven template, not dogma.
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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 3.8 Flash548 words
Starting a health and longevity journey doesn't require extreme diets or exhausting workouts. Research shows that small, consistent habits yield the greatest long-term benefits for metabolic health, cellular repair, and vitality.
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GPT-5.4 Pro785 words
Here’s a simple, beginner-friendly 1-month health and longevity plan built around 3 key areas: Nutrition Movement Recovery (sleep + stress) The goal is consistency, not perfection. Start small and make the habits easy enough to keep.
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Our Verdict
Gemini 3.8 Flash
Gemini 3.8 Flash
GPT-5.4 Pro
GPT-5.4 Pro

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

Gemini 3.8 Flash costs 48x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 3.8 Flash
Input
$0.75
40× cheaper
Output
$3.75
48× cheaper
GPT-5.4 Pro
Input
$30.00
Output
$180.00

Gemini 3.8 Flash is cheaper on both: 40× input, 48× output.

Where to run it

4 hosts, cheapest first

Gemini 3.8 Flash2 hosts
HostInOutContextUptime
Google Vertex AI$0.38 in·$1.88 out·1M·82.1% upGoogle AI Studio$0.75 in·$3.75 out·1M·99.9% up
GPT-5.4 Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$30.00 in·$180.00 out·1.1M—OpenAI$30.00 in·$180.00 out·1.1M·97.6% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

Writing DNA

Style Comparison

Similarity
43%
Gemini 3.8 Flash
GPT-5.4 Pro
63%Vocabulary50%
20wSentence Length35w
0.17Hedging0.70
4.0Bold7.5
2.4Lists8.3
0.01Emoji0.00
0.84Headings2.52
0.06Transitions0.01
Based on 27 + 12 text responses
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Model pages

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Gemini 3.8 Flash58 outputs, specs and price
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