A point is 1/72 inch. With that formula you can convert between inches and points. What's missing is the number of pixels in an inch. You can retrieve that by calling GetDeviceCaps( hdc, LOGPIXELSY ) which returns the number of pixels in 1 logical inch of your screen. A logical inch isn't exactly 1 inch if you measure it, but that isn't a problem as the point size only relates to logical inches on your screen.