The Last Project,
Our final Chance

One of our two largest clients at the design agency Ascentium, known today as SMITH, was T-Mobile. We’ve been working with them for several years, until one day they (sadly) announced they could no longer afford an external design agency like ours. This meant a major income loss, one we weren’t prepared for. So, this would be the last project we’d design for T-Mobile, and we wanted to impress them, make it a project they’d remember us by.

T-Mobile's Data CalculatorT-Mobile's Data Calculator

Redesigning the Data Calculator

T-Mobile’s data calculator is a tool intended to help customers decide which data plan best fits their needs by allowing them to evaluate their current data usage.

The calculator at the time looked like this -

Old Data CalculatorOld Data Calculator

We started out with usability sessions to test the current experience. We discovered it to be moderately confusing to most people.

The two main problems were, (1) People were unsure of what to enter for some of the questions. How many emails do I send per day; how many web pages do I view; Most people don’t know the answer to these. And (2), People don’t think in MB and GB. So, asking someone how many emails they send per day, in measurements of MB, is like me asking what you had for breakfast, in measurements of calories…. Most people just don’t know!


We made conceptual sketches to tackle some interesting design challenges such as how to indicate to people that an email requires less data than a video. We experimented with interactions that required physical force from the user, making some items virtually “heavier” and therefore harder to drag along the screen. In order to drag a movie file customers needed to use more force than to drag an email.


After several design iterations we settled on one which we wanted the client to implement. But how do you ensure the client will go for the design you want them to? Here’s what we did: we came up with two other designs, very radical in what they offered, placing the design we wanted them to choose as the desirable middle ground.

Solution 1 - Rearrange items on the page

The first design we introduced was extreme in that it involved almost no change to the layout they already had in place. We told T-Mobile - at almost no cost, you can improve the experience of your data calculator, just by rearranging elements on the page, bringing informational text to the top, reordering sliders so data heavy uses come first and adding names of plans to buttons. We did some testing, and this new hierarchy makes the page more understandable to users.

Solution 1Solution 1

Solution 2 - Tell Me Who You Are,
I’ll Tell You How Much Data You Use!

The second design, this time extreme to the other end, introduced a concept & style that were far from aligning with T-Mobile’s methodology. We called it the ‘Persona Calculator’, as it uses personas as a starting point. The top of the page asks the question: How do you use your device? The question is followed by representative persona examples, such as – the businessman heavy data user; the cool dude text only user; etc. The user can either choose a persona he identifies with most to see sample usages; or, users can ‘discover’ their persona by dragging the handles next to each icon which “pushes” water into the “well” on the right, indicating average data usage and giving a plan recommendation. The thickness of each water tube indicates how heavy an item is in terms of amount of data it uses (for example, email uses less data than games, therefore its tube appears thinner).

Solution 2Solution 2

Solution 3 - The Desired Middle Ground

We called it the ‘Super Simple Design’, and it’s meant to help even first time users use the tool easily while also having fun with it. Addressing the problems we saw in the original design, instead of giving numbers to indicate how many emails, web pages, and so on a person views per day, we decided to use words that are more intuitive such as ‘once in awhile’ and ‘regularly’. While using the calculator, as the user adds or subtracts data, a recommended plan gets highlighted.

When we tested this design, we noticed users didn’t need any explanations to use it. They started playing with it immediately, and had fun answering questions and getting immediate feedback on the page.

Solution 3Solution 3

The Final Look

Using this approach, we managed to lead the client to choose the design we were aiming for. In the process, we reached our three design guidelines:

(1) Simple: The controls should be known and obvious; It uses natural language and asks questions that the customer has to think very little about to answer meaningfully.

(2) Fun and playful: The data calculator should allow a customer to easily change settings or play with controls at no risk and it should not have perceived cost (page loads, wait time, etc). It should have immediate feedback and surprise customers at times.

(3) Informative: The data calculator should leave customers with a better understand of what they can potentially get out of their data plan, and feel confident that they are choosing the best data plan for their usage.

Final DesignFinal Design