MATLAB: How to set the figure width

figureMATLAB

I am trying to create a figure of width and height of 3 inches from an existing saved figure. How can I do this?
I would like to save this figure as a .png of the same size. Can I save this as png of this (3×3 inches) size.
I have also noticed that some parts of the labels disappears when saving it to .png. Why is this so? How do I prevent this?
Many thanks,

Best Answer

figure
set(gcf,'paperunits','inches')
set(gcf,'position',[0 0 3 3])
saveas(gcf,'fig1.png')