FontSize units
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" HorizontalAlignment="Center" VerticalAlignment="Center"> <StackPanel> <TextBlock Text="10 pixels" FontSize="10" /> <TextBlock Text="10 points" FontSize="10pt" /> <TextBlock Text="1 centimetre" FontSize="1cm" /> <TextBlock Text="0.2 inches" FontSize="0.2in" /> </StackPanel> </Window>