Develop Reference

is there an industry standard width for a screen to be considered mobile?

Currently, my app has 2 screen modes, desktop and mobile. The cut off for mobile is 725px.
Is this acceptable?

First off- don't think of things in terms of px. Because screens have different pixel densities densities. Back on the first android device, 160 pixels was 1 inch. Now its less than 1/2 inch on any decent phone, and less than 1/3 of an inch on a top end one. Screens are just that much better now. Instead, think of things in terms of physical size. The most common unit used on Android for that is dp, which is 1/160th of an inch.
The next thing to think about is orientation. A device can be portrait or landscape, and it will have different sizes in each. The general way you tell tablets vs phones is by how wide the shortest width is. A good rule of thumb is that a 7 inch tablet is about 600dp shortest width, and a 10 inch tablet is 720. Although that can vary a bit- the difference between a phone and a tablet is really marketing. (BTW, the reason why these aren't just 160x7 and 160x10 is because a 7 inch screen means a 7 inch length to the diagonal, not either side).
I'd take that concept and extend it to "desktop" vs "mobile". Decide what the smallest device you would consider a desktop is. See how many dp it is in shortest width (you can get that by multiplying the shorter of its screen dimensions by 160, then rounding down to a nice round number, you can find the size online usually). Make that your cutoff.

which resolution images to design for different android drawables folder

hey everyone
I've been facing drawables and layout related issues for a few days....
there are drawable-ldpi, drawable-mdpi, drawable-hdpi, drawable-xhdpi and drawable-xxhpdi folders in resources directory in android project
I've gone through the official android doc several times it definitely explains everything pretty welle.g scaling ratios for ldpi(0.75), mdpi(1), hdpi(1.5), xhdpi(2)but i couldn't find any information regarding which resolution to start with???
for example if i start designing graphics resources for xhdpi folder then which resolution i should go for???as there are many devices out there which lie in extra high density bucket but each having different resolutions, for example
Nexus4 (768x1280 xhdpi)
Nexus 10 (2560x1600 xhdpi)
Galaxy Nexus (720x1280 xhdpi)
same is the case with hdpi and mdpi bucket, lots of devices are there then which resolution images we should place in the corresponding folder????
please guide me guys m really in trouble

Look at #CommonsWare's answer.
I add that we are talking of dpi.
MDPI (160dpi)
HDPI (240dpi)
XHDPI (320dpi)
XXHDPI (480dpi)
XXXHDPI (640dpi)
Then:
to convert between dp and pixels use this formula:
px = dp × density ÷ 160

but i couldn't find any information regarding which resolution to start with?
For the vast majority of apps, if you are worrying about resolution, you are doing it wrong.
Ask yourself how you would write this as a Web app. Browser windows can have an arbitrary number of pixels of width and height, because the user can resize those windows as she sees fit. You are not going to design distinct imagery for a 1023x805 window instead of a 1037x740 window. Instead, you are going to take some approach that can handle a reasonable range of window sizes, perhaps with alternative artwork when you jump to a new range of window sizes.
Then, take that design approach, and apply it to your Android app. Focus on screen size and density, not resolution.
which resolution images we should place in the corresponding folder?
Resolution has nothing to do with density.

dpi has nothing to do with resolution. The dpi system is made so that a certain image will be (about) the same physical size no matter of the screen density, for example Google suggests that Buttons should be 48dp which is (about) 9mm on ANY density, but resolutions are different on any device, and including tablets you can't really worry about resolutions.
When making an app think about how you want to look, not in exact manners, for example "I want this line to have four buttons", make a LinearLayout with four buttons and you are done! (Sometimes you may want to include a horizontalScrollView depending on the size of the buttons).
Over time you will manage to understand this better, it's a matter of practise!

PSD file dimensions and resolution for Android app design

I heard and read different things regarding what should be the PSD file's dimensions and resolution for designing Android apps. Unfortunately, I came across different approaches for configuring PSD files, which I found confusing.
This page in Android Developer site says a lot about supporting screen sizes, but does not show how to configure the PSD files: http://developer.android.com/guide/practices/screens_support.html
So, in order to clarify this issue I will present the approach I take, and I would love to hear comments about it.
How I set the PSD:
I set the PSD's dimensions to 480x800 px (for portrait), and I set the resolution according to the current screen density I want to support, meaning:
320 Pixel/Inch for xhdpi
240 Pixel/Inch for hdpi
160 Pixel/Inch for mdpi
120 Pixel/Inch for ldpi
213 Pixel/Inch for tvdpi
(see the link above regarding screen support to understand why to use these numbers)
So what I do is design for the highest density I want for my app (say for example hdpi) and export, then I change the resolution the the next lower density (mdpi) and export and so on...
As for launcher icons, it is specified how to build the icons at:
http://developer.android.com/guide/practices/ui_guidelines/icon_design_launcher.html#size
All of the templates I found for icons used a 72 Pixel/Inch resolution in the PSD.
Edit:
So to make my question clear - is this approach correct? is it recommended?

Never assume a pixel size for your screen (e.g. 480x800 is a no go), you never know what your size or aspect ratio is going to be, and assuming these things is going to make your life very difficult in the future.
You should start at the highest resolution you can (it's not going to be long before XXHDPI is going to be more common), and work down from there. Determine what size the graphic needs to be. If you want it to be about an inch wide, multiply it by the density (e.g. 1 * 320 for XHDPI, 1 * 160 for MDPI, 1 * 240 for HDPI) to get the pixel size.
The DPI setting in Photoshop does not matter. People get confused and think it does, but for designing graphics for screens, it's irrelevant unless you want to check the physical size (e.g. if you set the document density to 320 dpi, and then check the image size, it should show you what the physical size -- such as inches -- is for a screen of that density). When creating a new document, you could create a new document at say 1 inch by 0.5 inch, at 320 dpi, and it will create it at the correct pixel size. I'd advise against it. Stick to pixel sizes that are multiples of 4 for the best quality when resizing.
Basically, take a more generic approach -- design the graphics you need at the highest resolution you plan to support, find areas where the size is flexible, and if necessary make stretchable 9-patch images for those areas. Then create versions for the lower densities once you've finished that.

Correct graphics for Android devices in regard to small/normal/large/xlarge and ldpi/mdpi/hdpi/xhdpi?

Im new to Android development and Im still a bit confused about making the correct graphics for the different devices. In this document there is a table listing different screen resolutions and density but it confuses me... Now lets take a example. I need a full screen background for my app, so making the largest background image 800x1280 for Galaxy Note seems about right for me (I don't want to support tablets, only phones), and then I could make a 720x1280 for Galaxy S3 and its likes and 480x800 version for Galaxy S2 and its likes, but where should I then place those image files?
It seems to me that all those devices are in the high density range, but then how do the devices use the correct graphics? Should I manually control this, or should I simply use just one and the same graphics for all devices and let Android scale it (then there are the problem with aspect ratio, how do I overcome that?)?
Thank you
Søren

In resource folder, you can create drawable directories according to width/height.
Then, you can use resource qualifiers, for width - wdp or Examples: w720dp,w1024dp etc.
for height hdp. Examples:h720dp, h1024dp etc.
Alternatively you can categories Screen size as small, normal, and large and can place your images in respective drawables.
Refer to this post : http://developer.android.com/guide/topics/resources/providing-resources.html#QualifierRules
small: QVGA low density and VGA high density.
normal: WQVGA low density, HVGA medium density, WVGA high density.
large: VGA and WVGA medium density screens.
xlarge: HVGA screen. The minimum layout size for an xlarge screen is approximately 720x960 dp units.
Everything is provided at developer site. Please refer to this link

The answer posted by yogeshhkumarr is correct, but it is worth noting that, depending on what sort of background images you are using, you may be able to make use of a 9-patch image to solve your problem without having to make multiple versions of the same image.

Creating base PSD to design Android App UI for mdpi, 320/480px device

I'm starting my first Android Phone design work. I have some experience with iPhone, iPad design but Android is totally different, I'm even not sure how I should create my base template.
Here is the device info I'm going to design. the app that will work only on this device, no need to multiple screen compatibility thing.
mdpi
256K color
3.5"
~165ppi pixel density
320px/480px
So, do I create my photoshop file for 320px/480px, 72px resolution, rgb?
Appreciate helps!!!

Google has made a whole site dedicated for your needs:
http://developer.android.com/design/index.html
In your case, your PSD settings should be setup like this:
NOTE/EDIT: Notice DPI is set at the default of 72. This is because DPI is meta data for printers. When you read DPI in phone specs, they are talking about the physical representation of how far apart the LCD is packed together. Resolution of the image (320x640) is the only thing you need to care about.

Have you looked at the Android Design site? It's specifically designed for... well designers.
Look at the devices display section and also the supporting multiple screens page to get an idea of what the general categories of screen sizes are and what an acceptable size and range for these is.
Android in general uses DIP's (Display independant pixel) so the actual pixels per inch depend on the screen you are creating art work for. You have to design for xlarge, large, medium and small screens with differed densities. General advice is to start with medium density screens and then you can increase density and decrease it in your artwork as needed. The link above gives the general dp dimensions of each screen size and density ranges of different types of screens. There should also be some info about converting dp to pixels.
While google frowns on what you are asking (designing for 1 device in particular), you said the device as 166ppi so you could just use 165 pixel / inch in your setting and set the height and width of the PSD depending on the size of your screen (whatever it's width and height is in inches).
This Smashing Magazine article on designing for android should really help. It's old but relevant.

Android is very different. If you learn how to do use the properties offered by android the right way it works greats.
Quote from developer.android.com
Each screen size offers different possibilities and challenges for user interaction, so in order to truly satisfy and impress your users, your application must go beyond merely supporting multiple screens: it must optimize the user experience for each screen configuration.
There are some tools you should get to know as well such as 'draw9patch'
The best thing to go off of is to simply create a layout in Photoshop just to get the layout down. It will not really matter what exact size as long as you have a rectangular shape. Make your layout and then start to make it fit in android.
Many great tutorials online, but as I mentioned before. Create your layout, then start to customize it for android by using tools such as draw9patch

Because you said your screen was ~165ppi, ppi = pixel per inch. Also, the Android docs describe 160dp as the generally accepted size for MDPI. – Ali Feb 7 at 22:22
so why in google samples
( ex : IDEName\AndroidSDK\samples\android-8\NotePad\res\drawable-hdpi ) ,
if open image ( ex : app_notes.png ) in photoshop and press ctrl + alt + i , to see resolution , its 72dpi !
but Ali says MDPI = 160dpi , HDPI = 240 , ...
so its must be 240dpi , not 72dpi.

The bitmap requirement is similar to preparing graphics for print vs. the Web. If you have any experience with print production, you’ll know that a 72 PPI image will look very pixelated and blurry when scaled up and printed. Instead, you would need to redo the image as a vector image or use a high-resolution photo and then set the file’s resolution at around 300 PPI in order to print it without any loss of image quality. Screen density for Android works similar, except that we’re not changing the file’s resolution, only the image’s size (i.e. standard 72 PPI is fine).
Android Smartphones And Display Sizes