I only have 5 hrs to prepare for market size. I have done tones of Cases but non market size. Any tips?

Hi there,

With 5 hours, you don’t need to overcomplicate things—just get comfortable with a simple, repeatable structure. The core formula you mentioned is spot on:

Market size = Volume × Price × Frequency

Here’s how to use it under pressure:

1. Pick an anchor (volume):
   • Start with population or number of customers/companies.
   • Narrow down logically (e.g., % urban, % with access, % likely to use product).
2. Estimate frequency of use:
   • How often does the customer buy/use it per year/week?
   • Anchor with everyday logic (e.g., coffees per day, Uber rides per week, dentist visits per year).
3. Add price per unit:
   • Keep it simple—round numbers to make math fast.
   • If you don’t know, use reasonable proxies (e.g., taxi fares for Uber, fast food meal price for Deliveroo).
4. Cross-check:
   • Ask yourself: does the result feel too big or small compared to GDP, industry reports, or common sense?
   • If yes, adjust one assumption.

Tips to practice in 5 hours:

• Do 3–4 drills on everyday markets (coffee in your city, Uber rides in London, toothpaste in Europe, etc.).
• Always state assumptions clearly (“Let’s assume…”). That matters more than the exact number.
• Round numbers aggressively (work with 50M instead of 47.3M).
• Talk through logic before doing math, so your structure shines even if your arithmetic is slightly off.

This way, you’ll show interviewers you can reason, structure, and sanity-check—even if you’ve never memorized a framework.

Happy to help you prep – feel free to reach out.

Best,
Evelina

Hi there,

With 5 hours, focus on the basics that will cover 80% of what you need.

1. Learn the core approaches
Top-down (start from population or macro data, narrow down with assumptions) and bottom-up (start from individual usage or sales, scale up). Be comfortable switching between them.

2. Practice 3–4 classic drills
Size the market for coffee in your city, the number of gas stations in the UK, or annual revenue for Netflix. Time-box each to 15 minutes, then review your logic.

3. Focus on structure, not the “right” number
Interviewers care more about how you break down the problem and justify assumptions than the final figure.

4. Keep math clean and round
Use easy numbers (e.g. 50 million instead of 48.7 million) and sanity check at the end.

If you do this for a few hours, you will walk into the interview with enough confidence to tackle most market sizing questions.

Best of luck!

This comment is not to you (too late now), but to other candidates who read this.

You are almost certain to have AT LEAST ONE market sizing exercise during a recruitment process with each single firm.

This means that YOU KNOW you WILL BE ASKED TO DO A MARKET SIZING. I see candidates spending a huge amount of time trying to memorize frameworks and buckets (which doesn't work, by the way), and not spending enough time on questions that you know you will be asked time and time again, and that you can successfully prepare beforehand for them. 

Market Sizing is one of them. Exhibit interpretation is another one. Brainstorming questions yet another. 

I can prepare a session and go over these topics explaining how to successfully prepare for these questions and what a WINNING answer looks like. 

It's like going to an exam, knowing the question you are going to get, and then nailing them very easily... saving precious brainpower (and time) for the really hard questions.

I assume the 5h have already passed by now. I hope you found a good way of looking at them. 

For other candidates still reading this thread, the high level approach for market sizing you should follow is this:

1. Clarify what needs to be sized and what is the unit of measurement
2. Present the approach to the interview, step by step. Align with them on it.
3. Generate assumptions for any missing data points. Align them with the interviewer.
4. Perform the computations and reach the final answer.
5. Interpret the result and comment on any sensitive assumptions you've made. 

Hope this helps!
Best,
Cristian

Hi,

hope your market sizing went well but for anyone still reading:

One thing most candidates overlook in market sizing is that interviewers aren’t just checking if you can crunch numbers. they’re checking if you can think like a consultant. A few things to keep in mind beyond what has been said:

• Define scope precisely upfront (“annual revenue for new car sales in Germany vs. all cars on the road”). Many candidates skip this and get off track
• Call out sensitivities (“this hinges on my assumption that 20% of households buy organic; if it’s 10%, the market halves”)
• Benchmark against something tangible (GDP %, household spend %, a similar industry) to sanity-check the result

Best,
Lukas

Hello there,

do the crafting cases free course, they have a session that cover market size in depth in about 2h with good drills for you to practice.

That, or hire a coach.

Best,

Mari

Hey, focus on structuring clearly (top-down, split by population × usage × price), practice a few quick drills out loud, and get comfortable making assumptions fast. Precision matters less than logic and sanity-checking your numbers.

best, Alessa :)