📄 Article
✓ Link checked
Free
Intermediate
Why we picked it
This is the most direct answer to your question from an investor who reads these slides for a living. It walks through why a bottoms-up number (customers times price they will pay) signals you understand your buyer, and treats the classic top-down TAM slide as a trap. You get a concrete formula and worked examples you can drop straight into your deck.
From
Underscore VC (Richard Dulude)
by Richard Dulude
12 min read
- Bottoms-up market size equals number of customers times price they will pay
- A bottoms-up slide signals you actually know your buyer and pricing
- Lead with bottoms-up and use the big top-down figure only as context
Open
underscore.vc →
📖 Book
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Paid
Beginner
Why we picked it
The single best thing ever written on customer conversations. It teaches you to ask about the customer's life and past behaviour, not your idea, so you can't be lied to. If a founder reads one thing before talking to a single customer, it's this.
From
momtestbook.com
by Rob Fitzpatrick
~130 pages
- Talk about their life, not your idea.
- Ask about specifics in the past, not opinions about the future.
- 'That's so cool, I'd totally buy it' is a compliment, not data, dig for commitment and evidence.
Open
momtestbook.com →
✍️ Essay
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Free
Intermediate
Why we picked it
This is the classic mental model for exactly your question: how customer count trades off against deal size. Janz maps five viable paths to $100M in revenue, from 1,000 enterprise customers paying $100k+ each (elephants) down to 10 million ad-monetized users (flies), so you can see where a low-count, high-value market sits and what it demands of you. Treat it as a lens for pressure-testing your own model, not a promise that any single path is right for you.
From
The Angel VC
by Christoph Janz
~12 min read
- There are several ways to reach $100M in revenue, and fewer, higher-value customers (elephants and deer) is a legitimate one, not a compromise.
- Each path demands very different skills: elephant hunting needs real enterprise sales muscle, while the mouse and fly paths need virality and marketing.
- The right question is not just how big your market is, but whether your acquisition channels are scalable and profitable for the segment you are chasing.
Open
christophjanz.blogspot.com →
✍️ Essay
✓ Link checked
Free
Advanced
Why we picked it
Before you sweat which side to seed, Gurley helps you judge whether your marketplace is even structurally worth building. He lays out ten factors (fragmentation, frequency, payment flow, network effects) that separate marketplaces that snowball from ones that stay empty. It is the investor lens on why some two sided ideas never reach liquidity no matter how hard you push.
From
Above the Crowd
by Bill Gurley
20 min read
- Great marketplaces enhance a market, they do not just aggregate it
- High fragmentation on both sides makes a marketplace more defensible
- Being in the payment flow is far stronger than sitting outside it
Open
abovethecrowd.com →
✍️ Essay
✓ Link checked
Free
Intermediate
Why we picked it
Most market sizing advice online is generic TAM SAM SOM filler. This one is written by an investor, backed by a survey of 30 VCs, and it is honest about the thing that matters: a big number pulled from an industry report proves nothing. It walks you through building the number bottom up (customers times what they pay you per year), which forces you to confront whether real people will actually pay, and that is the honest test of whether an idea can grow past a niche.
From
Pear VC
by Ian Taylor
~15 min read
- Size the market bottom up (count of real customers times annual revenue per customer), not by claiming a percent of some giant top down figure.
- TAM, SAM, and SOM are used loosely across the industry, so state your assumptions plainly instead of hiding behind the acronyms.
- Project the market out five or more years and include how you would actually reach and acquire customers, since a market you cannot serve is not your market.
Open
pear.vc →
📄 Article
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Free
Beginner
Why we picked it
A clean definition of the three market layers with the key distinction spelled out: TAM is the whole opportunity, SAM is what you can realistically serve, and SOM is what you will actually win. If the vocabulary still confuses you, this untangles it fast and shows why the SOM, your real near term slice, is the number that matters most.
From
Forum Ventures
by Forum Ventures
- TAM is the whole market, SAM what you can serve, SOM what you win
- SOM, your realistic near term slice, is what investors stress test
- Present both top down and bottom up to be credible
Open
forumvc.com →
📄 Article
✓ Link checked
Free
Intermediate
Why we picked it
This is written by Visible, a platform that sits on the investor side of the table, so it explains bottom-up sizing the way a VC actually reads it. It is direct about why the top-down number collapses under scrutiny and why the bottom-up build wins credibility, which is exactly the tension you are describing. Use it to decide what to lead with, then show top-down only as a sanity check.
From
Visible.vc
by Angelina Graumann
~10 min read
- Bottom-up sizing (count real customers, multiply by realistic revenue per customer) is more defensible because every assumption is one an investor can poke at and you can answer.
- A top-down number pulled from an industry report signals you Googled a big figure rather than understanding who buys, how many exist, and what they pay.
- The strongest move is to lead with your bottoms-up number and use top-down as triangulation: if the two diverge a lot, revisit your assumptions before the meeting.
Open
visible.vc →
📄 Article
✓ Link checked
Free
Intermediate
Why we picked it
A side-by-side of both methods that makes clear why you use bottom-up as your primary number and top-down only as a rough check. That distinction is exactly what protects you when the top-down Indian data is thin. Read it to decide which method to lead with in your deck.
From
Waveup
by Waveup
14 min read
- Bottom-up is defensible, top-down is only a directional check
- Use both and reconcile them against each other
- Lead with the method your data can actually support
Open
waveup.com →
📄 Article
✓ Link checked
Free
Beginner
Why we picked it
Written from an early-stage investor's chair, this walks the calculation with examples and is blunt that a bottom-up build beats a share-of-TAM guess. Antler backs pre-seed founders, so the advice is calibrated to exactly the stage you are at. Useful for seeing how a fund wants the number presented.
From
Antler
by Akshat Agarwal
- Early-stage investors prefer a bottom-up build over a share of TAM
- Worked examples show each of the three numbers being derived
- Present the assumptions so the number can be stress-tested
Open
antler.co →
📄 Article
✓ Link checked
Free
Beginner
Why we picked it
A short, plain read on why the one percent capture argument backfires and how to reframe your sizing around real buyers. It pairs well with the deeper essays if you want the idea quickly. Use it as a gut check before you commit to a top-down headline.
From
The Venture Crew
by Sahil S
8 min read
- Grabbing one percent of a big market is neither easy nor meaningful
- Investors want to see who buys, how many, and at what price
- Reframe from market share to demonstrated demand
Open
venturecurator.com →
📄 Article
✓ Link checked
Free
Beginner
Why we picked it
A practical guide from a startup accelerator that walks through gathering the data behind both top-down and bottoms-up estimates. It is useful when you need to actually source customer counts and pricing inputs. Use it to make sure the assumptions under your slide come from somewhere real.
From
MaRS Discovery District
by MaRS Discovery District
10 min read
- Good sizing rests on data you can point to, not intuition
- Bottoms-up estimates force you to find real customer inputs
- Document your sources so the number holds up under questions
Open
learn.marsdd.com →
📄 Article
✓ Link checked
Free
Intermediate
Why we picked it
This one focuses squarely on the method your short answer champions, building TAM up from real customer counts and pricing rather than slicing a giant number down. It is a good deep dive once you accept that bottom-up is the way and want the mechanics. Practical on ICP counts, adoption assumptions, and unit economics.
From
Qubit Capital
by Qubit Capital
- Build from your ideal customer profile count times annual value
- Ground adoption rates and pricing in observable segments
- Bottom-up assumptions can be tested, top-down percentages cannot
Open
qubit.capital →
📄 Article
✓ Link checked
India
Free
Beginner
Why we picked it
A short India-focused primer on what a first pitch should cover, including where market size fits and how it shapes how much you raise. It is practical for founders pitching Indian VCs for the first time. Read it to place your market slide inside a pitch that Indian investors expect.
From
Prime Venture Partners
by Prime Venture Partners
6 min read
- Market size influences both your deck and how much you should raise
- Keep the deck tight and let the market case be concrete
- Connect the size of the opportunity to your growth plan
Open
primevp.in →
✍️ Essay
Free
Intermediate
Why we picked it
This essay dismantles the seductive but hollow logic of if we just capture one percent of a huge market. It explains why that top-down framing signals lazy thinking to investors and what to do instead. Read it so you never lead with the number that undermines your credibility.
From
Angus Norton, Predict
by Angus Norton
9 min read
- The one percent of a giant market claim reads as a confession of laziness
- A defensible number is built from customers, not carved off an industry total
- Bottoms-up sizing shows you understand demand at a granular level
Open
medium.com →
