Lesson 2 of 2, 10 min
Sizing drills
Timed practice until the structure is automatic, across regions, currencies, and methods.
Math checked, facts checked against sources on 16 June 2026.
Key takeaways
- Estimation gets fast only with practice.
Estimation gets fast only with practice. Do these against the clock. Say your structure out loud first, then your assumptions, then calculate, then sanity-check.
How many households are in a UK town of 50,000 people, at about 2.5 people per household?
Now the same 50,000 people in an Indian town, at about 4.5 people per household. How many households?
How many liters of milk are drunk per day in a Dutch city of 1,000,000 people, if half the people drink about 0.25 liters a day?
A pizzeria in Milan sells 200 pizzas a day at EUR 12 each and is open 350 days a year. What is its yearly revenue, in EUR?
A Gulf country has 2,000,000 households. About 10 percent have a cat, and each spends about SAR 1,800 a year on cat food. What is the cat-food market, in SAR a year?
Supply-side: a hair salon in Singapore has 6 chairs, is open 10 hours a day, a haircut takes 30 minutes, and the chairs are busy 70 percent of the time. How many haircuts a day?
In a country of 1.4 billion people, 2 percent buy a product once a year at INR 500. What is the market size, in INR crore (1 crore is 10 million)?
In the smartphone example, 63 million owners aged 12 to 59 replace every 3 years, 6 million older owners now also replace every 3 years, and 1 million people buy a first phone. How many phones a year?
Terms in this lesson
Sources for this lesson (1)
- Recognized public explanations of case-interview concepts and terms
Next module: Profitability
That is the end of Guesstimates and market sizing. Profitability is next in the course.
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