How to show market size in your pitch deck
Based on advice from Aaron Harris (Y Combinator), Marc Andreessen, Bill Gurley · Updated 2 October 2026
Short answer
Show how big this can get and how much money it can make. Y Combinator's seed template says to convince the investor they'll make a lot of money with you. Marc Andreessen argues market is the most important factor in a startup's success, and Bill Gurley warns against sizing a new product by the old market it replaces.
What YC asks for
- What's the market?
- Is it going to be big, and will you make it big?
- How much money can this make?
- Convince the investor they'll make a lot of money with you.
Why investors care so much
In "The only thing that matters" (2007), Marc Andreessen calls market the most important factor in a startup's success, ahead of the team and the product. A great market pulls a product out of a startup.
Don't cap your market at today's size
In 2014 Bill Gurley argued that sizing Uber by the old taxi market was wrong. The San Francisco taxi and limo market was about $120 million a year, and Uber alone was already doing a multiple of that there. Faster pickups, cashless payment and lower prices created demand the old market never had.
In your deck
Check that your market slide answers YC's question, how much money can this make, and not just how big the category is today.
Real examples
Airbnb (2008) · slide 5
Airbnb sized its market in three steps: 2 billion+ trips a year, 560 million budget and online trips, and 84 million it aimed to win.
See the whole Airbnb deck
Uber (2008) · slide 17
Uber's 2008 deck used the US taxi and limo market, $4.2 billion a year. Gurley's point is that Uber grew far beyond it.
See the whole Uber deck
Notion (2013) · slide 7
Notion showed a horizontal product touching several markets, from design tools to enterprise software.
See the whole Notion deck
Read the originals
- How to build your seed round pitch deck · Aaron Harris (Y Combinator)
YC's seed deck template, with what goes on each slide.
- The only thing that matters · Marc Andreessen
Why the market matters more than the team or the product.
- How to miss by a mile · Bill Gurley
Why a better product can grow its market far past today's size.
Questions founders ask
- How do you show market size in a pitch deck?
- Answer Y Combinator's questions: how big is the market, will you make it big, and how much money can this make.
- Why do investors care so much about market size?
- Marc Andreessen argues market is the most important factor in a startup's success, more than the team or the product.
- Should I size my market by the market I'm replacing?
- Not only. Bill Gurley showed Uber quickly outgrew the old taxi market because a better product creates new demand.
Get your deck reviewed the same way.
Comments on every slide, the words to change highlighted, and the 3 fixes that matter.
Keep reading
- How to make the team slide in your pitch deck
YC's guidance for the pitch deck team slide: why your founders suit this problem. With Dropbox, YouTube and Airbnb's team slides.
- How to show your business model in a pitch deck
YC's guidance for the business model slide, and how Airbnb, Dropbox and LinkedIn showed how they'd make money.
- How to build a seed pitch deck: YC's template, slide by slide
Y Combinator's seed deck template explained slide by slide: title, problem, solution, traction, insight, business model, market, team and the ask.
- How many slides should a pitch deck have?
Y Combinator's seed template points to 10 to 15 slides. What famous decks like Airbnb, Coinbase, Intercom and Uber actually used.