The fake door test
The fastest way to find out if people want a product — before you build it. A fake door test advertises your idea as if it's real and measures who actually clicks, signs up, or tries to buy. Here's how to run one, set a pass/fail threshold, and read the result.
A classic pretotyping method · Built at Google, taught at Stanford
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What is a fake door test?
A fake door test — also called a painted door test — is a pretotyping method that measures real demand for a product or feature by advertising it as if it already exists — then counting how many people click, sign up, or try to buy. The “door” (a button, ad, email, or landing page) leads to an honest “coming soon” or waitlist page instead of the finished thing. It’s one of the fastest, cheapest ways to validate an idea: you learn whether people want it before building anything.
$0
Typical cost to stand up a basic fake door test
Pretotyping playbook
Days
Time to a clear demand signal, vs months to build
Exponentially sprints
88%
of AI pilots never reach production — most never tested demand
MIT, 2025
How to run a fake door test in 6 steps
Set your pass/fail threshold up front — before you see the result — so the test stays honest. See all 10 pretotyping methods →
State the hypothesis
Decide up front what demand would prove the idea — e.g. “5% of visitors will click Buy now.” Write the threshold down before you run.
Build the door
Create the button, ad, email, or landing page that presents the offer as if it's real. Make it specific and believable.
Drive real traffic
Send a representative audience — paid ads, your email list, or existing users — not friends and family who'll click out of loyalty.
Capture the click
Record who acts: clicks, sign-ups, emails left, or pre-orders. The action is the evidence, not a thumbs-up in a survey.
Show an honest follow-up
Land clickers on a transparent “coming soon” or waitlist page and offer to notify them. Never take money for something that doesn't exist.
Compare against your threshold
Measure the conversion rate against the pass/fail line from step 1. The number decides — build, iterate, or drop the idea.
How to tell a pass from a fail
Decide your threshold before you launch, then compare the signal against it. Here's what a healthy result looks like versus a weak one.
| Dimension | Healthy signal — pass | Weak signal — fail |
|---|---|---|
| Conversion rate | Meets or beats the threshold you set up front | Well below threshold despite real, relevant traffic |
| Who's clicking | Your actual target audience, from cold traffic | Mostly friends, team, or untargeted curiosity clicks |
| Follow-through | People leave an email or pre-order to be notified | Clicks, but no one will commit a single detail |
| Consistency | Demand holds across multiple traffic sources | One lucky channel; nothing repeatable |
Fake door testing, answered
What is a fake door test?
A fake door test is a pretotyping method that measures demand by advertising a product or feature as if it already exists, then counting how many people click, sign up, or try to buy. Clickers land on an honest 'coming soon' or waitlist page. It validates whether people want something before you build it.
Is fake door testing ethical?
Yes, when it's done honestly. You never charge for or promise a delivery date on something that doesn't exist. Clickers see a transparent 'coming soon' or waitlist page and can choose to be notified. The goal is to measure genuine intent, not to deceive — done this way it's a standard, widely used validation technique.
What's a good fake door conversion rate?
There's no universal number — it depends on the economics of your idea and your traffic source. The key is to set your pass/fail threshold before you run the test, based on how many sign-ups or purchases would make the idea worth building, then judge the result against that line rather than a generic benchmark.
Is a painted door test the same as a fake door test?
Yes. 'Painted door test' and 'painted door testing' are just alternative names for the same technique — you paint a door (a button, ad, or landing page) that looks real, then measure how many people try to walk through it. Whether you call it fake door testing or a painted door test, the method and the goal are identical: measure genuine demand before you build.
What's the difference between a fake door test and an MVP?
A fake door test runs before anything is built and often isn't functional at all — it tests raw demand. An MVP (minimum viable product) is a real, working minimal product that tests whether people will use and pay for a functional version. Fake door testing is faster, cheaper, and comes first.
How does the fake door test fit into pretotyping?
The fake door test is one of the classic pretotyping methods, alongside the Pinocchio, the Mechanical Turk, and the Façade. It's often the first one teams reach for because it produces a clear demand signal with almost no build. See the full set in our guide to what pretotyping is.
Want help running a fake door test on a real idea?
Twenty minutes with Leslie Barry. We look at one idea on your roadmap, design the test, set the pass/fail line, and tell you whether pretotyping is the right next step. No pitch.