1. Measure the diagonal of the screen with a ruler. Then use the corresponding conversion relationship to convert metric units, namely centimeters, into inches. For example, ask Siri directly how many centimeters equals how many inches.

2. Go to official website to find your own iPad model, and then look at the details of related equipment.

3. Proportional method. For example, if you know the screen size of your mobile phone, measure the length of iPad and mobile phone with a ruler.

4. Measure with an inch ruler.