Which resolution to target for a Mobile App?

Question

When desinging UI for mobile apps in general which resolution could be considered safe as a general rule of thumb. My interest lies specifically in web based apps. The iPhone has a pretty high resolution for a hand held, and the Nokia E Series seem to oriented differently. Is 240×320 still considered safe?

Answer 1

You mentioned Web based apps. Any particular framework you have in mind?

In many cases, WALL seems to help to large extent.

Here's one Article, Adapting to User Devices Using Mobile Web Technology exploiting WALL.

Answer 2

Not enough information...

You say you're targeting a "Mobile App" but the reality is that mobile could mean anything from a cell phone with 128x128 resolution to a MID with 800x600 resolution.

There is no "safe" resolution for such a wide range, and if you're truly targeting all of them you need to design a custom interface for each major resolution. Add some scaling factors in and you might be able to cut it down to 5-8 different interface designs.

Further, the UI means "User Interface" and includes a lot more than just the resolution - you can't count on a touchscreen, full keyboard, or even software keys.

You need to either better define your target, or explain your target here so we can better help you.

Keep in mind that there are millions of phone users that don't have PDA resolutions, and you can really only count on 128x128 or better to cover the majority of technically inclined cell phone users (those that know there's a web browser in their phone, nevermind those that use it).

But if you're prepared to accept these losses, go ahead and hit for 320x240 and 240x320. That will give you most current PDA phones and up (older blackberries and palm devices had smaller square orientations). Plan on spending time later supporting lower resolution devices and above all...

Do not tie your app to a particular resolution.

Make sure your app is flexible enough that you can deploy new UI's without changing internal application logic - in other words separate the presentation from the core logic. You will find this very useful later - the mobile world changes daily. Once you gauge how your app is being used you can, for instance, easily deploy an iPhone specific version that is pixel perfect (and prettier than an upscaled 320x240) in order to engage more users. Being able to do this in a few hours (because you don't have to change the internals) is going to put you miles ahead of the competition if someone else makes a swipe at your market.

Answer 3

@Adam Davis Thanks for a detailed response. I do hope to have some control over the type of mobile phones that would be supported. Right now I am at the planning stage. It's a small auction application to be used in informal trading floors. Most would have PDA grade phones, but the orientation varies from portrait to landscape and in between. I would have to count in as you have mentioned some screen real estate that would be taken up by on screen keyboards and window borders etc.

Right now I believe it would make sense for me to target about 2 resolutions and latter learn my customers best needs through feedback?

Being able to do this in a few hours (because you don't have to change the internals) is going to put you miles ahead of the competition if someone else makes a swipe at your market.

That sounds interesting. Prakash mentioned about WALL, I would take a look into that as well. :)

Answer 4

Right now I believe it would make sense for me to target about 2 resolutions and latter learn my customers best needs through feedback?

It's a chicken and egg problem.

Ideally before you develop the product you already know what your customers use/need.

Often not even the customers know what they need until they use something (and more often than not you find out what they don't need rather than what they need).

So in this case, yes, spend a little bit of time developing a prototype app that you can send out there to a few people and get feedback. They will have better feedback because they can try it out, and you will have a springboard to start from. The ability to quickly release UI updates without changing core logic will allow you test several interfaces quickly without a huge time investment.

Further, to customers you will seem really responsive to their needs, which will be a big benefit to people who's jobs depend on reaction time.