Market Size Calculator

Start with the form above. Type in your product or service, pick your business model (B2C, B2B, B2B2C or Marketplace), and choose the geography you want to size. Business stage is optional, but adding it gives the estimate some context about where you actually are.

Then run it. The tool searches the web for real market figures and builds your numbers on the TAM, SAM and SOM framework.

What you get back is two estimates: one top-down, one bottom-up. Every figure comes with its source and the year it was published, so you can see exactly where the number came from. And if the tool cannot find reliable data for your market, it says so instead of filling the gap with a guess.

Say you are testing a meal-kit idea in one country. You get the total demand, the slice you could realistically serve there, and the share you might win near term, each with citations attached.

One thing to hold onto from the start: this is a starting estimate, not a guarantee. It is the number you walk into a pitch with, and then have to defend.

What Are TAM, SAM and SOM?

Before the numbers make sense, you need the three layers they sit in. Investors ask for all three, and each one answers a different question.

TAM: The Whole Market

TAM means total addressable market. It is the full demand for what you sell, assuming you held 100% of it. No competition, no limits. For a cloud kitchen, that is all food delivery spend everywhere. Useful as a ceiling, and that is about it.

SAM: The Part You Can Serve

SAM stands for serviceable available market, also called serviceable addressable market. It cuts TAM down to the slice your business can actually reach. That is where the tool’s geography and business model inputs come in. Pick one city instead of the world, or a B2B model instead of B2C, and the layer narrows with it. Same cloud kitchen, but now only the delivery orders in your city that fit your menu and pricing.

SOM: The Part You Can Win

SOM is serviceable obtainable market: the share you can realistically capture in the near term. Business stage shapes this one. A pre-launch kitchen and a two-year-old brand with repeat customers do not aim at the same slice. Think first-year orders in that city, not every order.

Each layer feeds the next, which is why one input change moves more than one number. For formulas and layout, see this TAM SAM SOM template and examples guide. Waveup, a fundraising consultancy, explains why investors look for these three numbers.

Top-Down vs Bottom-Up Market Sizing

There are two ways to land on a market number, and this calculator runs both. One starts from the outside and works inward. The other starts from your customers and works outward. When the two land close, you have something you can defend. When they don’t, the gap points at the assumption you need to fix.

Top-Down: Start From the Industry Total

Top-down begins with someone else’s number. You take an industry spend figure from a published report, then cut it down to the share you could address.

Top-down market size = industry figure × addressable percentage.

Say a report puts global spending on freelancer tools at some large figure. Your share is the slice that matches your product, your business model and your region. The tool digs up that report figure through web search, then attaches the publisher and the year to it. That citation is the whole value of the method. You can open the source and check whether the scope really covers your market before you quote the number.

Bottom-Up: Start From Your Customers

Bottom-up builds the same market from the people who might actually pay you. You multiply who you can reach by what they would spend.

Bottom-up market size = reachable customers × average spend per customer.

Broken out, that works as population, penetration and spend multiplied together: target population × penetration rate × average annual spend.

Two traps sit in that formula. The first is scope: a global figure is the wrong input for a local decision, so use the population of the place you are actually selling into. The second is price: your list price is not average spend. Discounts, tier mix and churn all pull the real figure down, so use what customers end up paying.

How Your Four Inputs Shape Both

Your four inputs do the narrowing work in both formulas. Product and business model decide what counts as a customer and what they spend. Geography picks which population and which industry report the top-down method pulls from. Business stage sets the penetration rate you can honestly claim.

Take a subscription app for freelancers in one country. Top-down: global spending on freelancer tools, cut to that country and your price tier. Bottom-up: the number of freelancers there × a realistic first-year sign-up rate × your yearly plan price. Two routes, one market.

How to Check What the Market Size Calculator Gives You

Two routes, one market. So when the numbers land, put them side by side first. If top-down says 2 billion and bottom-up says 1.9 billion, that is close enough to work with. If one says 2 billion and the other says 200 million, something in your inputs is off.

A gap that big is not bad luck. It points at a specific assumption, and it is usually one of three things:

• Spend per customer. You may have used list price instead of what customers actually pay after discounts and churn.
• Geographic scope. A global industry figure feeding a local bottom-up count will never line up.
• How customers are counted. Companies, users and paying accounts are three different populations. Pick one and use it in both methods.

Some vendor guides treat a gap under 30% as the goal when reconciling the two methods, and flag ARPU, scope and customer counts when it drifts wider. Treat 30% as a rule of thumb from one blog, not an industry standard. What matters is that you can explain every difference.

Before You Put It in a Pitch

Here is the part people skip. An estimate is still an estimate, even when the arithmetic is clean. Open the sources this market size calculator attached to your figures and check that each one really covers your market and your year. A report published in 2021 about a different region will not survive investor questions.

Do that and you are not presenting a number you hope is right. You are presenting a number you can trace.

Final Thoughts

So run the tool once more with a single input changed. Swap the geography, or move the business stage forward, and watch which numbers shift. If SOM barely moves when you switch countries, one of your assumptions needs another look. Each variation takes minutes, and it shows you how sturdy the estimate really is.

Then keep the cited sources with your pitch notes. Not in a browser tab you will close by tomorrow, but pasted next to each figure. When an investor asks where a number came from, you answer in seconds instead of scrambling.

The estimate stays a starting point either way. What changes is that you can stand behind it, and that is what gets a market number taken seriously.