Prep RoomSign inStart free

Estimation & sizing questions.

68 estimation & sizing questions from the bank, ready to practice out loud.

Practice estimation & sizing

Learn the ideas first · free with an account

Fermi estimation: decompose, anchor, sanity-checkMarket sizing: top-down vs bottom-upSTAR and CARL: structuring your storySizing a market you have never sized

All 68 questions

YouTube videos uploaded per minuteEstimate how many YouTube videos are uploaded per minute globally.Breaking the problem downMid–senior
Daily coffee sales at StarbucksHow many cups of coffee does a typical Starbucks store sell in a day?Reasonable assumptionsEntry–mid
NYC bagel shop revenueEstimate the total revenue of all NYC bagel shops in a typical year.Breaking the problem downEntry–mid
Daily food consumption weightEstimate the total weight of all the food consumed in the US in a single day.Sanity Checking the order of magnitudeMid–senior
Flights over continental USHow many flights are in the air over the continental US at any given moment?Quick mental mathMid–senior
Social platform ad spendEstimate the annual ad spend on a major social platform's home feed. What's your confidence level?Communicating uncertaintyMid–senior
January gym memberships soldHow many gym memberships are sold in the US in January?Breaking the problem downEntry–senior
Weekly ATM cash withdrawalsEstimate the total amount of cash that's withdrawn from US ATMs in a typical week.Reasonable assumptionsMid–senior
Windows in flagship hotel buildingHow many windows are in your hotel chain's flagship building? Walk me through your estimate.Quick mental mathEntry–mid
Amazon daily package deliveriesEstimate Amazon's daily package delivery count in the US. Then sanity-check against any anchor you can think of.Sanity Checking the order of magnitudeMid–senior
Songs streamed on Spotify dailyHow many songs are streamed on Spotify per day?Breaking the problem downMid–senior
Paying customers at mid-market SaaSEstimate the number of unique paying customers a typical mid-market SaaS company has.Reasonable assumptionsMid–senior
Data center annual energyHow much energy does a major data center use in a year?Quick mental mathSenior–staff+
US legal opinions published annuallyEstimate how many pages of US legal opinions are published in a year.Breaking the problem downMid–senior
Recent AI startups GDPEstimate the GDP contribution of all the AI startups founded in the last 24 months.Communicating uncertaintySenior–leadership
National park summer visitorsHow many people visit a typical national park in a peak summer week?Reasonable assumptionsEntry–senior
Black Friday card transactionsEstimate the number of credit card transactions processed in the US during the Black Friday weekend.Quick mental mathMid–senior
US home renovation spending annuallyEstimate the total dollars spent on home renovation in the US in a year. Then check it against any cross-reference you can think of.Sanity Checking the order of magnitudeSenior–staff+
Doctors' appointments in US weeklyHow many doctors' appointments happen in the US in a typical week?Breaking the problem downMid–senior
Open-source maintenance hours globallyEstimate the total developer hours spent annually maintaining open-source code globally.Reasonable assumptionsSenior–leadership
NYC Friday pizza deliveriesEstimate the number of pizzas delivered in NYC on a typical Friday evening.Quick mental mathEntry–mid
Seed-stage AI VC investmentEstimate how much money venture capital firms collectively invested in seed-stage AI startups last year.Communicating uncertaintySenior–leadership
Uber driver daily milesEstimate the total miles driven by Uber drivers in a single city in a day.Breaking the problem downMid–senior
Knowledge worker annual emailsEstimate the number of emails sent by a typical knowledge-worker in a year.Reasonable assumptionsEntry–mid
Office repainting timelineEstimate how many days it would take to repaint every surface in a 200,000-square-foot office building.Quick mental mathMid–senior
US dog grooming service revenueEstimate the total US revenue of dog grooming services. Then check it against pet ownership statistics if you can.Sanity Checking the order of magnitudeMid–senior
Streaming video storage per hourHow much storage does a single hour of a popular streaming video service occupy globally?Breaking the problem downSenior–staff+
Manhattan office spaceEstimate the total number of square feet of office space in Manhattan.Reasonable assumptionsMid–senior
McDonald's meals served globally dailyEstimate the number of meals served by all McDonald's globally in a single day.Quick mental mathEntry–mid
Airline widebody fuel costsEstimate the annual cost to a major airline of fuel for its widebody fleet. Where would your answer be most fragile?Communicating uncertaintySenior–leadership
Gas station weekly salesEstimate how many gallons of gasoline are sold at a typical suburban gas station in a week.Breaking the problem downEntry–mid
Tennis balls in school busHow many tennis balls fit inside a school bus? State your key assumptions clearly.Reasonable assumptionsEntry–mid
Smartphones in use in CaliforniaEstimate the number of smartphones currently in use in California. Does your answer pass a basic sanity check against the state's population?Sanity Checking the order of magnitudeEntry–mid
Movie theater Saturday revenueA movie theater has 8 screens. Estimate total ticket revenue for a typical Saturday. Walk me through your mental math.Quick mental mathEntry–mid
Manhattan Friday pizza deliveriesEstimate the number of pizzas delivered in Manhattan on a typical Friday night.Breaking the problem downEntry–mid
California EV charging stationsHow many electric vehicle charging stations currently exist in California? Walk me through your reasoning.Reasonable assumptionsMid–senior
US Black Friday card transactionsEstimate the total number of credit card transactions processed in the US on Black Friday.Breaking the problem downMid–senior
AWS data centers operating globallyHow many data centers does AWS operate globally? Give me your best estimate and confidence interval.Communicating uncertaintyMid–senior
LA weekday rideshare tripsEstimate the number of ride-share trips taken in Los Angeles during a typical weekday.Reasonable assumptionsEntry–mid
Airline customer support tickets dailyHow many customer support tickets does a major airline handle per day? Sanity-check your answer.Sanity Checking the order of magnitudeMid–senior
Amazon US warehouse square footageEstimate the total square footage of warehouse space Amazon uses in the US.Breaking the problem downSenior–leadership
US daily pharmacy prescriptionsHow many prescriptions are filled at US pharmacies in a typical day?Quick mental mathEntry–mid
Software engineers employed at GoogleEstimate the number of active software engineers currently employed at Google worldwide.Reasonable assumptionsMid–senior
US annual baby diaper salesHow many baby diapers are sold in the US each year? Walk through your assumptions.Breaking the problem downEntry–mid
US venture capital deployed annuallyEstimate the total value of venture capital deployed in the US last year. What's your confidence level?Communicating uncertaintySenior–leadership
Netflix content added monthly globallyHow many hours of content does Netflix add to its platform each month globally?Reasonable assumptionsMid–senior
US summer day gasoline volumeEstimate the number of gallons of gasoline sold at US gas stations on a typical summer day.Quick mental mathEntry–mid
Fortune 500 annual job applicationsHow many job applications does a Fortune 500 company receive per year? Sanity-check against hiring volume.Sanity Checking the order of magnitudeMid–senior
Las Vegas hotel room inventoryEstimate the total number of hotel rooms available in Las Vegas.Breaking the problem downEntry–mid
Windows lines of codeHow many lines of code are in the Windows operating system? Give me a range and explain your reasoning.Communicating uncertaintySenior–leadership
US daily MRI scans performedEstimate the number of MRI scans performed in the US each day.Reasonable assumptionsMid–senior
Smartphones in active use worldwideHow many smartphones are currently in active use worldwide? Walk me through your estimate.Breaking the problem downMid–senior
McDonald's US annual revenueEstimate the total annual revenue of all McDonald's locations in the US.Quick mental mathEntry–mid
Cybersecurity incidents at major banksHow many cybersecurity incidents does a major bank detect and respond to each month?Reasonable assumptionsSenior–leadership
Los Angeles container volumeEstimate the number of shipping containers that pass through the Port of Los Angeles each day. Then sanity-check it.Sanity Checking the order of magnitudeMid–senior
Patents IBM files globally annuallyHow many patents does IBM file globally in a typical year? Give me your best estimate and confidence interval.Communicating uncertaintySenior–leadership
Wall Street investment banking employeesEstimate the total number of employees working in investment banking across all Wall Street firms.Breaking the problem downMid–senior
US annual plastic waste generationHow many tons of plastic waste does the US generate each year?Reasonable assumptionsMid–senior
Stripe API call rateEstimate the number of API calls Stripe processes per second during peak shopping hours. What assumptions are you making?Breaking the problem downSenior–leadership
US mutual fund revenueEstimate the total annual fee revenue of the US mutual fund and ETF industry.Breaking the problem downMid–senior
Typical financial advisor client assetsEstimate the assets a typical US financial advisor manages for clients.Reasonable assumptionsEntry–mid
Index fund expense cutYour firm cuts the expense ratio on a $500 billion index fund family by 2 basis points. Estimate the revenue impact, and how much new AUM it takes to offset it.Quick mental mathMid–senior
US 401(k) plan total assetsEstimate the total assets held in US 401(k) plans.Sanity Checking the order of magnitudeMid–senior
US home sales commissionsEstimate how many homes are sold in the United States in a year, and the total commission pool that creates.Breaking the problem downMid–senior
Apartment building absorption rateA 280-unit apartment building opens in a metro of one million people. Estimate a reasonable monthly absorption rate and how long it takes to reach 95% occupancy.Reasonable assumptionsMid–senior
Rental house cash flowA rental house costs $380,000 and rents for $2,400 a month. Roughly, in your head: what's the gross yield, and does it cash-flow with 20% down at a 7% mortgage?Quick mental mathEntry–mid
Manhattan office space square footageEstimate the total square footage of office space in Manhattan, and sanity-check your answer from a second direction.Sanity Checking the order of magnitudeMid–senior
Active real estate agentsEstimate how many licensed real estate agents are active in the US, and what share closed more than five transactions last year. Be explicit about your confidence in each step.Communicating uncertaintyMid–senior