Px represents pixel, which is the most basic point for displaying data on the screen; Pt is a point, which is a common unit in the printing industry, equal to 1/72 inch.

Px is the pixel unit pt is the absolute unit. Their respective advantages are that px can achieve the desired effect on the computer screen, and it can achieve the desired effect on printers and other high-resolution devices. Pt is a unit of measurement of fixed length, which can be measured with measuring equipment. Absolute units are of limited use because they cannot be scaled and are usually used only when it is known which output medium they are used on. However, in most cases it is best to use relative units.

In Windows, the default display setting defines text as 9696 pixels/inch. This definition shows that 1px=1/96 inch. Referring to the concept of pt, 1pt=1/72 inch, it can be concluded that in this setting, 1px=0.75pt, and the common Song typeface 9pt=12px.

The conversion rule of pt and px is also very simple. The conversion formula is: pt=px times 3/4. For example, 1024px × 3/4=768pt size.