Toothbrush Test

The toothbrush test is a simple check question from the technology industry. It goes: Would people use this product once or twice a day? And would it make their life a bit better in the process? Anyone who answers both questions with yes has, according to this rule, something valuable on their hands. The name comes from the toothbrush, because hardly any other object is picked up so reliably twice a day. The rule became well known through Larry Page, one of the two founders of the search engine Google. He is said to have used it to decide whether Google should acquire another company.

Habit beats revenue forecast

Normally, a company is evaluated using numbers. You look at revenue, profit, and growth over recent years. But with young technology companies, these numbers often don’t exist at all. Many run at a loss for years before any money comes in at all. The toothbrush test replaces the missing numbers with a different question: Is a habit forming here?

Behind this lies a solid economic consideration. A product that is used daily becomes a fixed part of everyday life. Users are then reluctant to switch to a competitor, because switching takes effort. This inertia is called customer retention in the industry. Over the years, it is worth more than a single large sale.

The rule also guards against a typical trap. Some products sound impressive but are only needed twice a year. A tax filing app is a good example of this. It can be very useful, but it never becomes a habit. The toothbrush test filters out such cases before the price is even discussed.

What Page asked about Nest and YouTube

The test is not a calculation formula but a thinking aid. You imagine how an ordinary person spends an ordinary day. Then you check at which points the product shows up in it. If it appears several times a day, the test is passed. If it only shows up on special occasions, it fails.

Larry Page is said to have asked this question during several major acquisitions. In 2006 Google bought the video platform YouTube, and in 2014 the thermostat maker Nest. In both cases, it was less about the revenue at the time than about the role in everyday life. People watch videos in the evening, and adjust the heating in the morning and at night. The price of 3.2 billion dollars for Nest only made sense under this assumption.

The second half of the question is important. It’s not enough for something to be used often. It should also actually improve life. Otherwise, any game that is addictive would pass the test brilliantly. This is exactly a common point of criticism: the rule can easily be interpreted in a way that treats pure screen time as value.

The rule in the debate about AI assistants

The term appears today mainly in business news. When a corporation buys a start-up for a large sum, journalists ask for the reasoning. The toothbrush test is then a convenient explanation for prices that seem exaggerated at first glance. Founders also use it when they want to convince investors.

The term comes up especially often these days in connection with artificial intelligence programs. Providers of chatbots like ChatGPT or Gemini want to achieve exactly this status. Their stated goal is for people to open the program several times a day without thinking about it. The number that counts here is called daily active users, meaning people who launch the product at least once on a given day. If it rises, this is considered evidence of a genuine habit.

Still, one should not overestimate the test. It is a rule of thumb, not proof. There are very successful companies that clearly fail the test, such as providers of flight booking systems. And there are products with daily use that have never made money. The rule helps with filtering, but it does not replace a thorough examination of the business model.