Manufacturers often give data of the body, but rarely give data of the actual display area. Inches are not an intuitive figure for a screen.
If you've recently been shopping for a tablet and aren't sure how big the screen actually is, try this tool.
Select the machine you want, print this pdf on A4 paper using the 100% size, check that it is printed at 100% scale using an ID or bank card placed in the middle box.
Cut along the dotted line, and the part you get is the actual display area of the screen.
You can compare it to what you want to display and see if it's big enough.
厂商们经常会给出机身尺寸的数据，但很少给出实际显示区域的数据。英寸对于屏幕来说并不是一种直观的数据。
如果你最近在选购平板电脑，不清楚屏幕究竟有多大的话，可以试试这个工具。
选择你要的机器，使用 100% 尺寸在 A4 纸上打印这个 pdf，使用身份证或银行卡放在中间的框中检查是否为 100% 比例打印。
沿虚线裁开，你得到的部分就是屏幕的实际显示面积。
你可以把它和你想显示的东西比一比，看看够不够大。