5 Mobile Form Factors to Consider When Building Your App

When planning the development of a mobile app there is more than the OS to be considered. The times when you could just blow-up your app screen X2 are long gone, it was actually a bad implementation even in the early days of mobile apps.

Today there are actually 5 form factors you need to consider per each major OS (Android and iOS). Add to this the different form factors of Windows devices and we are well over 10  (and we didn’t talk about Laptops and Desktops).

Classifying them by size:

Device	Screen size
Small Phones	3.5 Inches or smaller
Medium Phones (e.g. iPhone)	3.5 to 4.9 inches
Phablets (e.g. Galaxy Note & iPhone 6+)	5 to 6.9 inches
Small Tablets (e.g. Kindle Fire)	7 to 8.4 inches
Full-size Tablets (e.g. iPad)	8.5 inches and larger

Source: Flurry

Considering these form factors doesn’t mean you need to build a different app for each. It does mean you need to prioritize between them and make a sound decision how you are going to tackle user experience across all the devices.

While each app has its target audience characteristics, knowing the state and trend of the market is important.

Flurry of Yahoo published a report showing the trends and distribution between these form factors. The report gives strong evidence that users are asking to super-size their devices. Phablets have grown from 3% (Feb/2013) to 6% (Jan/2014) to 20% (Mar/2015) and the form factor to take the toll is the medium mobile device.

One may think that the release of iPhone 6+ in September 2014 is the reason for this increase but iPhone 6+ accounts for only 4% of iOS active users. Android Phablets on the other hand account for 36% of Android active users. This means we should expect additional growth of Phablets as iPhone users upgrade and have to make a choice between the 6 and 6+.

Size maters

Building a different look and feel for different screen sizes is common today. At some companies there are different teams per each device form factor and the app is different not only in UI but in its functionality and features.

The type of the device and its size affect the way users use the device, for what they use it and where. Do users touch the screen with one hand or 2 hands is one question to ask.

The features of the app should be adjusted based on the type and size of the device. For example, in a service that embeds WebRTC video call and collaboration in it, on the larger devices it will be possible to share the screen and see all participants while on the smaller devices it will be required to switch between views and see in one of them the collaboration session and the participants in another. It would be nice to add the ability to zoom in and out in smaller screens in order to see the screen details, something not required on large tablets.

Device types, their screen size, processing capabilities and usage patterns impact application requirements and those not taking this into account end up with bad user experience on the devices they neglected.

Microsoft Windows 10

In the Microsoft Windows 10 reviews in MWC Barcelona and the Microsoft Build conference, Microsoft talked about Universal App and Continuum.

This approach comes to tackle the diversity of devices, their size and the usage. What Microsoft claims to achieve through Universal App is that a Windows 10 application will be able to run on all Windows 10 devices and adapt itself (including UI and functionality) based on the device it runs on. Additionally, through Continuum, user will be able to switch between touch and mouse & keyboard UI modes in laptops that can be switched to tablet mode and Surface tablets to which a keyboard can be connected.

This sounds really great, reality will tell if this lives up to its promise.