There isn't currently a way from Xamarin.Forms itself but we have it implemented as PCL compatible interface in Xamarin.Forms.Labs which you can get from NuGet or source code from GitHub: https://github.com/XForms/Xamarin-Forms-Labs

There isn't currently a way from Xamarin.Forms itself but we have it implemented as PCL compatible interface in Xamarin.Forms.Labs which you can get from NuGet or source code from GitHub.

https://github.com/XForms/Xamarin-Forms-Labs

IDevice has IDisplay property with the information; height, width, pixel density for X & Y and couple of extension methods to calculate sized in inches.

Sample page for getting information from the device:

https://github.com/XForms/Xamarin-Forms-Labs/blob/master/samples/Xamarin.Forms.Labs.Sample/Pages/Services/ExtendedDeviceInfoPage.cs

       #region Display information
    var display = device.Display;
    var displayFrame = new Frame();
    if (display != null)
    {
        displayFrame.Content = new StackLayout()
        {
            Children =
            {
                new Label() { Text = display.ToString() },
                new Label() { Text = string.Format("Screen width is\t {0:0.0} inches.", display.ScreenWidthInches()) },
                new Label() { Text = string.Format("Screen height is\t {0:0.0} inches.", display.ScreenHeightInches()) },
                new Label() { Text = string.Format("Screen diagonal size is\t {0:0.0} inches.", display.ScreenSizeInches()) }
                        }
                    };
    }
    else
    {
        displayFrame.Content = new Label() { TextColor = Color.Red, Text = "Device does not contain display information." };
    }

    stack.Children.Add(displayFrame); 
    #endregion

Creating an exact inch-by-inch frame on all platforms regardless of display properties:

https://github.com/XForms/Xamarin-Forms-Labs/blob/master/samples/Xamarin.Forms.Labs.Sample/Pages/Services/AbsoluteLayoutWithDisplayInfoPage.cs

public class AbsoluteLayoutWithDisplayInfoPage : ContentPage
{
    public AbsoluteLayoutWithDisplayInfoPage(IDisplay display)
    {
        this.Title = "Absolute Layout With Display Info";
        var abs = new AbsoluteLayout();
        var inchX = display.WidthRequestInInches(1);
        var inchY = display.HeightRequestInInches(1);
        var originX = display.WidthRequestInInches(display.ScreenWidthInches() / 2);
        var originY = display.HeightRequestInInches(display.ScreenHeightInches() / 2);

        abs.Children.Add(new Label() { Text = "1\"x\"1\" blue frame" });

        abs.Children.Add(new Frame()
            {
                BackgroundColor = Color.Navy,
            },
            new Rectangle(originX - inchX/2, originY - inchY/2, inchX, inchY));

        abs.Children.Add(new Frame()
            {
                BackgroundColor = Color.White
            },
            new Rectangle(originX - inchX/16, originY - inchY/16, inchX/8, inchY/8));

        this.Content = abs;
    }
}

To get to the device info either set your DI resolver or use a static container. All 3 platforms have a singleton device calls with static CurrentDevice property:

resolverContainer.Register<IDevice>(t => WindowsPhoneDevice.CurrentDevice)
resolverContainer.Register<IDevice>(t => AppleDevice.CurrentDevice)
resolverContainer.Register<IDevice>(t => AndroidDevice.CurrentDevice)