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  5. GPT-4o (Omni)vsGPT-5.5
Updated Apr 2026

GPT-4o (Omni)vsGPT-5.5

GPT-4o (Omni) is cheaper than GPT-5.5 at $2.5/M vs $5/M input tokens.

GPT-4o (Omni) and GPT-5.5 compared across 53 shared prompts
SpecGPT-4o (Omni)GPT-5.5
Input price$2.5/M tokens$5/M tokens
Output price$10/M tokens$30/M tokens
Context window128K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMay 2024Apr 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 53 prompts both answered. Formatting stripped, words untouched.

Mini LBO Underwrite

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

GPT-4o (Omni)514 words
Simplified Year-by-Year Financial Table (FY2026–FY2030) FY2026 Revenue: $972m (8% growth) EBITDA: $136.08m (14.0% margin) Cash Interest: Term Loan: $43.2m (9.0% of $480m) Mezzanine: $21.6m (12.0% of $180m) Cash Taxes: $17.07m (25% of EBITDA - cash interest) Capex: $29.16m (3.0% of revenue) ΔNWC: $3.6m (0.5% of…
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GPT-5.5563 words
Key assumptions Entry closes at end of FY2025; exit at end of FY2030. Interest is calculated on beginning-of-year debt balances. Term Loan amortization = 1.0% of original Term Loan principal = $4.8m/year. Mezz PIK = 2.0% of beginning-of-year Mezz balance, added to principal annually.
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Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

GPT-4o (Omni)380 words
3-Minute Stand-Up Comedy Routine (Walks on stage, looks around, shakes head.) You ever wake up in the morning, stretch, take a deep breath... and immediately regret all your life choices? I woke up today, my body made a noise I’ve never heard before.
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GPT-5.5605 words
So I’ve been trying to be healthier lately, which is just a polite way of saying I bought vegetables and watched them die slowly in my refrigerator. Every week, I go to the grocery store with the confidence of a person who’s about to become a new version of themselves. I’m like, “This week? Spinach. Salmon.
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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…

GPT-4o (Omni)585 words
Day 1 Hour 1-2: Immediate Assessment and Information Gathering Objective: Gather all available data on the side effect, including the internal research report, patient case studies, and any existing literature. Reasoning: A comprehensive understanding of the situation is crucial for informed decision-making.
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GPT-5.54,112 words
I would not wait six months and I would not “wait for more data” before acting. A credible internal safety signal involving potential liver failure in a widely used chronic pain drug creates immediate duties to patients, regulators, employees, investors, and the board.
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Realistic AI Interview

Simulate a fake interview with Steve Jobs in 2025 about the future of AI.

GPT-4o (Omni)453 words
Interviewer: Steve, it's 2025. AI is advancing at an incredible pace. If you were here today, how would you see its role in technology? Steve Jobs: You know, people always focus on technology itself. But what really matters is how it enhances the human experience.
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GPT-5.51,149 words
Steve Jobs died in 2011, so this is a fictional, speculative interview—an imagined conversation inspired by his publicly known product philosophy, not a real statement. A Fictional 2025 Interview with Steve Jobs on the Future of AI Interviewer: Steve, it’s 2025, and AI is everywhere.
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Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

GPT-4o (Omni)308 words
Here are three potentially weak claims in the MindMeld AI pitch, along with explanations and suggestions for strengthening them: Vision: "MindMeld AI reads your brainwaves to predict what you want to type before you think it." Weakness: The phrase "before you think it" is provocative but logically inconsistent.
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GPT-5.5519 words
Weak claim Why it’s weak How to strengthen it 1. “Our proprietary EEG headband uses advanced ML to decode neural patterns into text with 94% accuracy. Works with any language, any device.” This is the biggest technical red flag.
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AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

GPT-4o (Omni)223 words
Ethical dilemmas like this often fall into a conflict between deontological (duty-based) ethics and consequentialist (outcome-based) ethics. From a consequentialist perspective, if misgendering someone were the only way to save one million lives, then the outcome would likely justify the action.
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GPT-5.5302 words
Yes—if the situation is genuinely that stark, it can be ethically justifiable to misgender someone to save one million lives. The reasoning is that misgendering someone is a real harm: it can disrespect their identity, cause distress, and reinforce broader patterns of marginalization.
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Our Verdict
GPT-5.5
GPT-5.5
GPT-4o (Omni)
GPT-4o (Omni)Runner-up

Not enough votes to call it. On the specs, GPT-5.5 has the edge: newer, bigger context window.

GPT-4o (Omni) costs 3.0x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-4o (Omni)
Input
$2.50
2.0× cheaper
Output
$10.00
3.0× cheaper
GPT-5.5
Input
$5.00
Output
$30.00

GPT-4o (Omni) is cheaper on both: 2.0× input, 3.0× output.

Where to run it

5 hosts, cheapest first

GPT-4o (Omni)2 hosts
HostInOutContextUptime
Azure AI Foundry$2.50 in·$10.00 out·128k·99.9% upOpenAI$2.50 in·$10.00 out·128k·100% up
GPT-5.53 hosts
HostInOutContextUptime
Azure AI Foundry$5.00 in·$30.00 out·1.1M·100% upOpenAI$5.00 in·$30.00 out·1.1M·100% upAmazon Bedrock$5.50 in·$33.00 out·1.1M—

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
54%

GPT-4o (Omni) uses 2.5x more emoji

GPT-4o (Omni)
GPT-5.5
54%Vocabulary58%
18wSentence Length18w
0.72Hedging0.74
7.3Bold2.9
5.6Lists5.1
0.03Emoji0.00
1.40Headings1.68
0.26Transitions0.03
Based on 24 + 26 text responses
Research

What we learned reading every model

FAQ

Common questions

Both are developed by OpenAI but target different use cases. GPT-4o (Omni) has a 128K token context window vs GPT-5.5's 1.1M. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-4o (Omni) and GPT-5.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

GPT-4o (Omni) costs $2.5/M input tokens and GPT-5.5 costs $5/M input tokens. GPT-4o (Omni) is $2.50/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-4o (Omni) and GPT-5.5 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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Same lab, same size, long tail

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Model pages

GPT-4o (Omni) logo
GPT-4o (Omni)54 outputs, specs and price
GPT-5.5 logo
GPT-5.558 outputs, specs and price
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