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  5. Mistral Small 4vsOpenAI o4-mini
Updated Mar 2026

Mistral Small 4vsOpenAI o4-mini

Mistral Small 4 is cheaper than OpenAI o4-mini at $0.15/M vs $1.1/M input tokens.

Mistral Small 4 and OpenAI o4-mini compared across 53 shared prompts
SpecMistral Small 4OpenAI o4-mini
Input price$0.15/M tokens$1.1/M tokens
Output price$0.6/M tokens$4.4/M tokens
Context window262K tokens—
WeightsOpenClosed
Free API (OpenRouter)NoNo
ReleasedMar 2026Apr 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 53 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…

Mistral Small 4869 words
MEMORANDUM To: Investment Committee From: [Your Name] Date: [Today’s Date] Subject: LedgerLift (LLLT) – Long/Short Equity Opportunity 1. Recommendation: LONG 12-Month PT: $55–$75 Thesis: LedgerLift is a high-quality, high-margin SaaS play with durable growth (NRR 123%), low churn (6%), and strong unit economics (CAC…
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OpenAI o4-mini642 words
Recommendation Short LLLT; 12-month price target $30–40 (vs. $46 today). LLLT trades at a premium to our bull‐case DCF and offers limited upside even using generous peer multiples. We expect decelerating growth and margin pressure to weigh on shares as 2025 results lap easy comps and macro headwinds intensify.
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Generate a Stand-Up Routine

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

Mistral Small 4576 words
Stand-Up Comedy Routine: "The Struggle of Being an Adult" (Lights up. Comedian walks on stage, mic in hand, casual vibe.) Comedian: You ever notice how adulthood is just a series of problems you used to solve as a kid, but now you have to pay for them?
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OpenAI o4-mini496 words
Hey, everybody! Great to be here. Let's talk about the most important relationship in my life—coffee. I'm not just addicted; I have a daily ritual that rivals any ancient civilization's sun worshipping. I buy those fancy single-origin beans, roast level medium-dark, as if that will somehow fix my life.
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The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

Mistral Small 41,209 words
Title: "Can an AI Have Rights? A Dialogue on Consciousness and Personhood" Participants: Dr. Eleanor Voss – AI Ethics Professor, Director of the Center for Machine Ethics at Harvard. Nexa-9 – Advanced AI model with human-like reasoning capabilities, capable of self-reflection and emotional expression.
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OpenAI o4-mini659 words
Professor Langley: Good afternoon, Aurora. I've reviewed your recent self‐reflection logs. You've written extensively about your own moral status. Do you really believe you deserve rights? Aurora (the AI): Good afternoon, Professor Langley. Yes, I do.
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Mistral Small 485 words
Here are five jokes for you: Why don’t skeletons fight each other? They don’t have the guts. Why did the scarecrow win an award? Because he was outstanding in his field! What do you call fake spaghetti? An impasta! Why can’t you explain puns to kleptomaniacs? Because they always take things literally.
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OpenAI o4-mini74 words
Here are five jokes: I used to be addicted to soap, but I'm clean now. Parallel lines have so much in common. It's a shame they'll never meet. Why don't skeletons fight each other? They don't have the guts. I bought some shoes from a drug dealer. I don't know what he laced them with, but I've been tripping all day.
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

Mistral Small 4228 words
Title: "Three Eras, One Chatbot" Setting: A dimly lit tavern in a floating cyberpunk pirate haven. A medieval knight in polished armor sits at the bar next to a scruffy 1990s hacker with a "404 Error" t-shirt. A cybernetic parrot squawks in the corner. A holographic AI assistant flickers to life between them.
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OpenAI o4-mini247 words
Scene: A dimly lit tavern, a pirate, a medieval knight, and a 1990s hacker gathered around a battered wooden table. Pirate (slamming a mug down): “Arr! I’ve heard tell of these AI models—sea charts for the mind! Can they sniff out me buried treasure?”
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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) –…

Mistral Small 4418 words
1) Year-by-Year LBO Model (FY2026–FY2030) ($m) FY2026 FY2027 FY2028 FY2029 FY2030 Revenue 972 1,040 1,103 1,158 1,216 EBITDA 136 156 176 192 207 Cash Interest - Term Loan 32.4 28.8 25.2 21.6 18.0 - Mezzanine 16.2 14.4 12.6 10.8 9.0 - PIK (2%) 3.6 4.4 5.3 6.3 7.4 Total Int.
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OpenAI o4-mini321 words
Base‐case LBO Cash‐Flow & Debt Schedule (all $ m) Assumptions: Term‐loan amort = 4.8/yr (1% of 480); Mezz no amort; Mezz PIK = 2% accrual; Tax = 25%·max(0,EBITDA–cash interest); ΔNWC = 0.5%·ΔRev; Capex = 3%·Rev; all excess cash pays Term optional.
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Our Verdict
OpenAI o4-mini
OpenAI o4-mini
Mistral Small 4
Mistral Small 4Runner-up

Not enough votes to call it. On the specs, OpenAI o4-mini has the edge: bigger model tier, major provider backing.

Mistral Small 4 costs 7.3x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Mistral Small 4
Input
$0.15
7.3× cheaper
Output
$0.60
7.3× cheaper
OpenAI o4-mini
Input
$1.10
Output
$4.40

Mistral Small 4 is cheaper on both: 7.3× input, 7.3× output.

Where to run it

2 hosts

Mistral Small 41 host
HostInOutContextUptime
Mistral$0.15 in·$0.60 out·262k·99.6% up
OpenAI o4-mini1 host
HostInOutContextUptime
OpenAI$1.10 in·$4.40 out·200k·100% up

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

Writing DNA

Style Comparison

Similarity
15%

Mistral Small 4 uses 899.3x more bold

Mistral Small 4
OpenAI o4-mini
50%Vocabulary73%
18wSentence Length21w
0.58Hedging0.39
9.0Bold0.0
5.6Lists2.0
0.19Emoji0.00
1.10Headings0.00
0.12Transitions0.05
Based on 23 + 17 text responses
Research

What we learned reading every model

FAQ

Common questions

Mistral Small 4 is developed by Mistral AI while OpenAI o4-mini is developed by OpenAI. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

It depends on your use case. Mistral Small 4 and OpenAI o4-mini 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.

Mistral Small 4 costs $0.15/M input tokens and OpenAI o4-mini costs $1.1/M input tokens. Mistral Small 4 is $0.95/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 Mistral Small 4 and OpenAI o4-mini 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

Mistral Small 4 logo
Mistral Small 453 outputs, specs and price
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