🧠 Read time: 4 min
Let’s be real:
Most startup decks butcher market sizing.
It’s either
🧚 inflated nonsense (“$1T+ market!”)
or
🤷♂️ a forgotten slide thrown in last minute with a pie chart from Statista.
But here’s the truth:
Get this slide right, and it can raise you millions.
Get it wrong, and it screams “rookie”.
So today, I’m breaking down exactly how to nail your TAM / SAM / SOM with maximum signal.
This is the kind of post you’ll come back to before every raise.
Save it.
💡 What is TAM / SAM / SOM?
Forget the acronyms for a sec. Here’s the real-world breakdown:
TAM: Total Addressable Market
= How big the entire market could be if you took it all.SAM: Serviceable Available Market
= What % of that market you could realistically serve today.SOM: Serviceable Obtainable Market
= What you can actually win with your current resources, product, and team.
Hot take:
TAM is theory.
SOM is what gets you funded.
🧠 Founders love big TAMs.
Investors love believable SOMs.
Let’s say you’re building a new platform for short-term rentals:
TAM: 1.9B global bookings per year (Airbnb-level)
SAM: 532M bookings in your key markets, on digital platforms
SOM: 10.6M bookings = what you realistically aim to capture
This is pulled straight from Airbnb’s legendary pitch deck.
Why it works:
They didn’t just say “huge market.”
They said, “Here’s how we eat a piece of it, and how fast.”
🔢 Three ways to calculate it (choose one that works for you):
1. Bottom-up (strongest)
Start with actual numbers:
→ # of potential customers × avg. annual spend = TAM
Way more accurate than top-down. Investors love this.
2. Value Theory
If you're inventing something new:
→ How much would someone pay to solve this problem?
Think Spotify vs CDs. You’re pricing based on pain relief, not precedent.
3. Top-down (meh)
Find a big stat and carve out a slice.
→ Use only if you don’t have better data, and always cite your source.
Example in fast food:
🎯 Bonus concept: Earlyvangelists
They’re not your full market.
They’re your beachhead.
→ The people who are feeling the pain the most. Your first customers, innovators & early adopters. They are quite easy to convince… They settle for a product that is not yet finished and therefore not perfect.
Find them, serve them well, and your beachhead strategy compounds.
→ The early majority, late majority, and the laggards on the other hand expect your product or service to be ready to use or deploy.
💸 TAM → ROI: The investor lens
Your job isn’t just to show a big market.
It’s to rapidly cross the Chasm and show how that market turns into a fat return.
Here’s how the math might play out:
SOM = €5M revenue in 2 years
EBITDA margin = 25%
Valuation = 8x EBITDA = €10M
If investor owns 20%, they 8x their investment.
If you scale to €12M revenue, that ROI jumps to 19.2x.
Simple story. Clear math. Real upside.
🧩 TL;DR → What a good TAM/SAM/SOM slide includes:
✅ Clear bottom-up numbers
✅ A believable SOM (beachhead)
✅ Real customers in mind, not just market stats
✅ Bonus points: show how your SOM scales over time
🛠️ Want a template?
I built this canvas for you:
👉 The TAM/SAM/SOM Template
It plugs into your pitch deck. No fluff. All signal.
🔥 Pro tip:
If you’re raising in September, now is the time to prep your data room, your deck, and your market map.
That’s why I’ve bundled 40+ of the best resources behind the scenes in the premium plan:
Top 50 pitch decks that raised billions
SAFE & dilution calculator
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Investor update templates
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→ Upgrade now for 20% off until Aug 31
(It’s 73% cheaper than monthly. And will likely pay itself back 100x if you’re fundraising.)
Yoann