How to Determine the Screen Width in Terms of Dp or Dip at Runtime in Android

Density Bucket	Screen Density	Physical Size	Pixel Size
ldpi	120 dpi	0.5 x 0.5 in	0.5 in * 120 dpi = 60x60 px
mdpi	160 dpi	0.5 x 0.5 in	0.5 in * 160 dpi = 80x80 px
hdpi	240 dpi	0.5 x 0.5 in	0.5 in * 240 dpi = 120x120 px
xhdpi	320 dpi	0.5 x 0.5 in	0.5 in * 320 dpi = 160x160 px
xxhdpi	480 dpi	0.5 x 0.5 in	0.5 in * 480 dpi = 240x240 px
xxxhdpi	640 dpi	0.5 x 0.5 in	0.5 in * 640 dpi = 320x320 px

Get screen width and height in Android

Using this code, you can get the runtime display's width & height:

DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int height = displayMetrics.heightPixels;
int width = displayMetrics.widthPixels;

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In a view you need to do something like this:

((Activity) getContext()).getWindowManager()
                         .getDefaultDisplay()
                         .getMetrics(displayMetrics);

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In some scenarios, where devices have a navigation bar, you have to check at runtime:

public boolean showNavigationBar(Resources resources)
{
    int id = resources.getIdentifier("config_showNavigationBar", "bool", "android");
    return id > 0 && resources.getBoolean(id);
}

If the device has a navigation bar, then count its height:

private int getNavigationBarHeight() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
        DisplayMetrics metrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(metrics);
        int usableHeight = metrics.heightPixels;
        getWindowManager().getDefaultDisplay().getRealMetrics(metrics);
        int realHeight = metrics.heightPixels;
        if (realHeight > usableHeight)
            return realHeight - usableHeight;
        else
            return 0;
    }
    return 0;
}

So the final height of the device is:

int height = displayMetrics.heightPixels + getNavigationBarHeight();

Android - Puzzles about conversion between dp and pixel

You are looking at the wrong place in the formula. To see how many dp equals one px in different density, lets rearrange the formula:

px = dp * (dpi/160)
dp = px / (dpi/160)

Now for 1px, in mdpi devices:

dp = 1 / (160/160) = 1dp

In hdpi devices:

dp = 1 / (240/160) = 0.666666667dp

You can see that 1px equals less dp in higher density devices

Android : is a width of 160dp equals to 100% of the screen width?

No. 160 dp is 1 inch (or extremely close). What they're saying is if you had a 160 dpi (dot per inch) device, then 1 pixel=1dp. 160 dpi was common in the early days of Android.

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