The Toothbrush Impact Test

How can we know if customers will want or need a new product or service?

Henk Kleynhans
3 min readNov 28, 2017

You may have heard that for a product to be truly successful it has to be three things: desirable, feasible and viable:

I come from an engineering background and I like to tinker, especially with new gadgets and technologies. And whenever I play with a new piece of tech, I inevitably think of ways in which it could be used to make my life better.

Cloud Controlled Remote Laser Toaster using an old DVD writer and a Raspberry Pi (aka Toast-as-a-Service, or TaaS)? Yeah, baby!

Well, it might be technically feasible… but I usually find out pretty quickly that most of my (brilliant) ideas aren’t really viable — they’d struggle to make money. And most often I don’t even get to the point of asking whether it is desirable: “Do people actually want remotely printed toast?”

Start with desirability

Design thinking starts deliberately with the first question: Do people want this? And one of the best ways to find this out, is to build a cheap, low-fidelity prototype and simply show it to people.

But even simple questions can get murky. People might love an idea, but won’t necessarily spend money on it. And sometimes people will ask for something that may be familiar, but will soon be obsolete. As Henry Ford said: “If I had asked people what they wanted, they would have said faster horses.”*(*Alternative Fact Check)

Early prototypes for good ideas can also get highly negative feedback. Automatic elevators suffered from this: go ask people to get into a closed box, in a vertical tunnel, and noisy motors… no thanks, I’ll take the stairs!

The Toothbrush Impact Test

So how can we know what customers want if asking them doesn’t give us a clear answer? One way of determining a real need is by using The Toothbrush Impact Test.

Is your idea solving a problem that:

1. Affects many people

2. Affects them frequently

3. Has a significant impact if not solved?

Or simply put: is it something most people will use twice a day?

For example, an elevator prototype might not receive great customer feedback, but elevators are used by many people, several times a day and have a significant impact on productivity, building design and urban planning.


There is no single perfect way to know what is truly ‘desirable’, but using a combination of customer interviews and tools such as the Toothbrush Impact Test, we could more easily prioritise products, features and initiatives and then rapidly test to see whether we got it right.

Sadly, my Cloud Controlled Laser Toast Printer doesn’t pass the Toothbrush Impact Test. But who knows? Maybe there’s a niche market somewhere. (Feel free to register your interest by leaving a comment below!)

Did you know…? The first public elevator was a steam-powered theme park ride called an “ascending room”!



Henk Kleynhans

Built Wi-Fi networks in Africa, lobbied governments on spectrum reform, connected the Dalai Lama to Desmond Tutu. Head of Product (Insurance)