I'm developing a web application which is quite information heavy. This means that every pixel available in the screen for display helps a lot, to avoid the UI looking too cluttered and to display relevant data.
I was wondering: which is the "common" screen resolution? Years ago it was something like 1024×768, but nowadays it must be something much higher. I can't rely on what I use as I'm a developer and I probably have bigger screens and resolution than the average Joe user.
So, where can I find the currently recommended resolution for webapps?
That really depends on where you are in the world. Worldwide 1366x768 is still the most common, however 1920x1080 is the only resolution that is actually increasing in take-up (presumably because this seems to be the standard widescreen for modern laptops).
The website StatCounter.com should help give you some further knowledge on this.
HOWEVER, bear in mind that just because certain resolutions are more common than others this it doesn't actually take into account how wide the user has their browser window. Unfortunately, there are few known measurements for this statistic (Google analytics used to provide this, but have ceased supporting it).
Keep in mind that laptops and desktops are no longer the only web-enabled devices. The iPad has a resolution of 1024x768, the iPhone 4 has a resolution of 960x640, assuming you use them in landscape mode.
The choice of minimum screen resolution all comes down to how many users you are willing to exclude.
If you do not have a history of resolution data for your specific users, one option is to use public, global usage statistics as a guideline. Using one such source of global data, I created the following graph to help convey the state of desktop screen widths at a glance.
Why don't you design adaptively for 'whatever you have available'?
I agree with Jon that one should be careful to use the full screen resolution as a base when designing web apps. He is also right when he states that the wide screen variant of 768 is very common these days.
I recently experienced, however, some very good reasons to decrease my own screen resolution policy. TVs and multimedia laptops now uses the HD standard as their resolution. That means that it is a good chance that several users to have 1280×720 as their resolution. Targeting 768 as height might be a little bit to much for many users.
Who is this app for? If it's internal facing (ie corporate environment), talk to IT and see what resolution employees screens are set at. Especially look at the employees that would be working in the app the most.
If it's a public facing app, think about what data you have about your users' resolutions. If you're redesigning, check the analytics on the current site and get a sense of what resolutions your users are running. You might notice a pattern here (ie people tend to have very high resolutions since they are power users, etc), but chances are it'll be all over the place.
Think about the data you're presenting. If it's a lot of grids, maybe a fluid layout is best. Then the user can stretch their screen to show more of the data they need.
Designing for 1024 is a safe route for the web, but it's lazy if you aren't trying to learn more about your users before making a decision.
The 1024*768 should still remain as a common sense. Otherwise it really depends on your audience. If you make a website or app for designers for example, you should optimize for much higher resolution like 1680*1050.
You should test it or ask from your desired audience, but 1024*768 is still a must!
In an ideal world there would be different (CSS) styles for different resolutions and devices. :)