Applications · 13 min read

How to Answer "How Do You Know People Want This?" on the YC Application

Short answer

"How do you know people want this?" is the question that separates founders who have done the work from founders who have a good idea. YC asks it in the application and asks it again in the interview. The answer they are looking for is never a market size figure, never a McKinsey report citation, and never a logical argument about why the problem should matter to people. The answer is always specific, first-hand evidence — things you observed, conversations you had, money someone paid you, behavior that happened without you asking for it.

What the Question Is Really Asking

The question has two layers:

Layer 1: Is the problem real? Does the problem you are solving actually affect real people in a meaningful way, or is it a problem that exists in theory but that actual users are comfortable living with?

Layer 2: Is your specific solution the one people want? Even if the problem is real, your specific approach to solving it may not be the one users will adopt. Evidence that people want your specific solution — not just that the problem exists — is what answers this field completely.

Most founders answer Layer 1 adequately. Very few answer Layer 2 with the same specificity. The applications that get interviews answer both.

The Evidence Hierarchy

Not all evidence is equal. YC partners weight evidence in this order — highest to lowest:

1. Revenue from paying customers Someone gave you money for your product. This is the strongest single signal. Even one payment of ₹500 is more credible than a 500-person waitlist. State the number of paying customers, the revenue, and the billing cycle.

2. Repeat usage by active users Users who came back to use your product without being prompted. Repeat usage signals that your product delivered enough value the first time to earn a second interaction. Cite the retention rate and the timeframe: "71% of users who signed up in our first month have used the product at least once in the last 7 days."

3. Behavior-based pre-commitment Users who took a meaningful action to signal demand before your product was fully built. This includes: paying a deposit or pre-order, joining a waitlist with personal contact information, asking when they can pay, or spending significant time in a pilot session. These are demand signals that required something from the user.

4. Qualitative evidence from user interviews Specific things specific users said in interviews that reveal genuine pain. Not "they said the problem was important" — the specific words, the specific emotion, the specific moment when you realized the problem was more acute than you had assumed. "One pharmacy owner told me she had cried the last time she found ₹80,000 of expired medicine in a single stock check. That moment is when I knew this was worth building."

5. Proxies for demand in the absence of direct evidence If you have none of the above yet, proxies include: search volume for related queries, forum posts where people describe the pain in their own words (Reddit, Facebook groups, Quora), the existence of workarounds people have built themselves (a pharmacy owner who built their own Excel sheet to track expiry because nothing else worked), or industry reports that quantify the cost of the problem.

Proxies belong at the bottom of this list because they are the least founder-generated form of evidence. Use them to supplement stronger evidence, not as a substitute for it.

The Answer Layer: How to Write This Field

Lead with your strongest evidence signal. State it in one sentence with a specific number. Follow with your second strongest signal. Then add one qualitative detail that makes the evidence feel human rather than statistical.

Template: "[Strongest signal with number]. [Second signal with number]. [One qualitative observation that reveals the depth of the problem]."

Example for a company with paying customers: "We have 23 paying customers at ₹2,800/month, with month-2 retention of 89%. 11 of our customers came from referrals — pharmacy owners recommending us to other pharmacy owners in their WhatsApp groups without being asked. One customer, a pharmacy owner in Nashik, told us he flagged ₹34,000 of near-expiry stock in his first week and called us to say it had paid for a full year of our software in a single use."

Example for a pre-revenue company: "We have no revenue yet. We have conducted 67 interviews with independent pharmacy owners across Pune, Nashik, and Aurangabad over 8 weeks. 43 of 67 said they currently track stock in notebooks or Excel. 11 agreed to use our beta version and give us weekly feedback without any incentive. 3 of them independently asked us when they could pay — one sent us a UPI payment request before we had a payment system set up."

Both examples are strong because they lead with specific numbers and add a human detail that reveals genuine demand rather than politeness.

The Data Layer: What Counts as Evidence vs What Doesn't

Counts as strong evidence:

  • Paying customers with specific MRR or ARR figure
  • User retention rate with a timeframe
  • Referrals that happened without incentive
  • Users who came back after trying the product
  • Pre-orders or deposits collected
  • LOIs or pilot agreements signed
  • User interviews with specific verbatim observations
  • Users who built their own workarounds to solve the problem

Counts as weak or no evidence:

  • Market size reports from consulting firms
  • Survey data from third-party sources
  • Number of people who said they "would use" your product
  • Number of people who said the problem was "important"
  • Friends and family who tried the product
  • App store downloads with no engagement data
  • Social media impressions or follower counts
  • Competitor revenue as a proxy for your potential

The distinction is this: strong evidence requires someone other than you to have taken an action. Weak evidence requires only that someone said something.

The Context Layer: Why This Field Is Misunderstood

Most founders treat this field as a market validation field — a place to prove the market is big and real. That is wrong. The market validation belongs in the market size field. This field is specifically about evidence that people want your specific product.

The confusion leads to the most common failure mode in this field: answering "is the problem real?" with market data and never answering "do people want your specific solution?" with user evidence.

A pharmacy software market that is worth $4B tells a partner that pharmacy software is a real market. It tells them nothing about whether pharmacy owners want your WhatsApp-native approach versus the desktop SaaS approach that every other pharmacy software company uses.

The specific evidence that people want your specific solution — not just that the category has demand — is what this field is asking for.

6 Mistakes Founders Make in This Field

Mistake 1: Leading with market size instead of user evidence Market size answers "is this market real?" not "do people want this product?" Put market size in the market size field. Put user evidence here.

Mistake 2: Citing survey results where users said they would use your product Stated intent and actual behavior have almost no correlation in consumer research. "80% of respondents said they would use a product like this" is worth almost nothing as evidence. What people do with their money, time, and attention is evidence. What they say on a survey is noise.

Mistake 3: Describing user interviews without specifics "We talked to 50 potential customers and they validated our hypothesis" is a nearly useless sentence. Which customers? What did they say specifically? What were their exact words when they described the problem? One specific quote from one specific user interview is more credible than a generic count.

Mistake 4: Counting friends, family, or colleagues as validation Users who agreed to try your product because of a personal relationship do not constitute demand evidence. Their behavior may not represent the behavior of users without that relationship. Specifically note when you are citing evidence from users who had no prior relationship with you — cold user evidence is significantly more credible than warm.

Mistake 5: Confusing app downloads with user demand 10,000 app downloads says something interesting about top-of-funnel curiosity. It says nothing about whether your product delivers enough value that users will pay for it or return to it. Pair any download figure with a 7-day or 30-day retention rate and the answer becomes meaningful.

Mistake 6: Future-tense evidence "We plan to conduct user interviews" and "we will validate with a pilot cohort" are not evidence. This field asks how you know people want this — in past tense. If you cannot answer this question with past-tense evidence, you are not ready to apply.

Special Cases

Hardware products: Physical prototype usage by real users is strong evidence. "We gave 5 farmers an early version of our soil sensor and 4 of them asked to keep it after the pilot ended" is a compelling demand signal for hardware.

Regulated markets: Sometimes direct user validation is limited by regulatory constraints — you cannot let patients use a medical device before approval, for example. In this case, lead with clinical validation, physician interview data, or regulatory progress as a proxy for demand.

Enterprise B2B: Enterprise buyers will not pay without going through procurement. But signed pilots, LOIs, and specific named companies in your pipeline are credible demand signals for enterprise. "We have 2 signed pilot agreements with [type of company] and 3 companies in active final evaluation" is strong enterprise demand evidence even without revenue.

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FAQ

Frequently asked questions

What is the best type of evidence that people want your product for a YC application?
Paying customers with retention data is the strongest evidence. Even one customer who paid any amount of money and came back to use the product a second time is more credible than any other form of evidence at early stage. The payment signal proves willingness to pay. The retention signal proves the product delivered enough value to justify continued use. Together, they answer both layers of the question — the problem is real and your specific solution addresses it.
Can user interviews alone be enough evidence for a YC application?
User interviews can be sufficient evidence at pre-revenue stage when they are numerous, specific, and reveal a genuine non-obvious insight. The threshold YC partners seem to look for is roughly 40-80 interviews with a consistent and surprising pattern in what users told you. Fewer interviews or interviews that only confirm what was already obvious ("yes, tracking inventory manually is inefficient") are weaker. Interviews that reveal a specific hidden truth — "the person managing inventory is not who I thought it was" — carry more weight.
How do you show demand evidence for a product that is not yet built?
Through pre-commitment signals — actions users took before the product existed. Pre-orders, deposits, letters of intent, paid pilots for manual versions of the product, and users who asked when they could pay are all demand signals that do not require a finished product. The classic YC example is doing things that do not scale — running a manual version of your product for early users and charging for it. 5 people paying for a manual service is stronger evidence than 500 people on a waitlist for a free product.
Is a large waitlist good evidence that people want your product?
A large waitlist is a weak demand signal unless it includes conversion data. 1,000 people on a waitlist for a free product tells partners that your marketing worked. 200 people on a waitlist where 40 gave you their phone number and asked to be called when you launch tells partners that the demand is more genuine. The strongest waitlist evidence includes: how users found out about you, what they gave you to sign up (email only vs. phone + payment method), and how many converted to paid when you launched.
Should you include negative feedback from users in this field?
You can, if it led to a meaningful product change that increased demand. "Our first 10 users told us the product was too complex and 7 stopped using it. We simplified to a single core workflow and our next cohort of 15 users had 87% retention in month 2." That narrative is more credible than a straight positive story — it shows you listen to users and iterate based on what they tell you.
What if your evidence is from a different market or customer segment than your target?
Disclose it and explain the transfer. "Our current 12 paying customers are in Mumbai, but we are targeting tier 2 cities. We have conducted 30 interviews in Pune and Nashik that confirm the same pain pattern exists there, and we are migrating our sales effort to those markets starting next month." That is honest and credible. Applying evidence from one segment to another without acknowledging the gap is a mistake that partners will surface in the interview.
Does YC weight qualitative evidence (user stories) differently from quantitative evidence (metrics)?
Yes — quantitative evidence (specific numbers with units) is weighted more heavily in the application review, while qualitative evidence (user stories, specific quotes) is more valuable in the interview where partners can probe it in real time. In the written application, lead with numbers. Add one human detail to make the evidence feel real. Save your most compelling user stories for the interview where you can tell them with the conviction they deserve.
How should a marketplace address this question — which side of the market should they show evidence for?
Both. A marketplace has two sets of users and demand must be validated on both sides. An application that shows strong demand from buyers but does not address supply availability — or vice versa — raises the chicken-and-egg concern. Show your strongest evidence for the side you have more data on, then name specifically what you have done to validate the other side: "We have 23 paying buyers. On the supply side, we have onboarded 8 pharmacy chains who have agreed to process returns through our platform."
What is the minimum evidence needed to submit a credible YC application?
Based on patterns across applications that received interviews, the minimum viable evidence tends to be one of: 3+ paying customers at any price point, 30+ user interviews with a specific non-obvious insight, or 5+ active pilot users with documented usage data. Below these thresholds, the application is asking partners to fund an idea rather than a business. Most founders who apply below this threshold would improve their odds significantly by spending 4-6 more weeks generating evidence before submitting.
How do you frame evidence from a manual or concierge version of your product?
Directly and specifically. "We have been running a manual version of this service for 8 users over the past 6 weeks. We do the work manually using WhatsApp and spreadsheets. 7 of the 8 users are paying ₹1,500/month for the manual service and 5 have asked when the automated version will be available." This framing is credible because it shows real users getting real value from the core service proposition even before the software is fully built. It also shows that you are doing things that do not scale — a classic positive signal in YC applications.
Should I mention if a user tried the product and churned in this field?
Yes, if you can explain why and show what changed as a result. A churned user honestly discussed is more credible than a suspiciously perfect retention story. "We had 3 users churn in our first cohort. Two said the workflow was too manual. One said they did not have time to train their staff. We rebuilt the onboarding flow and our second cohort has had zero churn in 6 weeks." That narrative shows product iteration based on real feedback, which is itself a positive signal.
How do you show demand evidence for a two-sided marketplace before either side has fully committed?
Show evidence from whichever side you have built first, then describe the specific actions you have taken to validate the other side — even if that validation is qualitative. "We have 12 pharmacy owners actively listing return requests. On the distributor side, we have had detailed conversations with 6 distributors, 3 of whom have seen our demo and said the workflow matches how they currently handle returns manually. Two of them asked when they could onboard." That answer shows real evidence on one side and directional validation on the other.

An independent resource · Not affiliated with Y Combinator · Last updated 2026-02-01