To get your bedside table height just right, aim for the top of the surface to...

https://www.normalbookmarks.win/the-golden-rule-for-bedside-tables-is-comfort-aim-for-your-tabletop-to-sit

To get your bedside table height just right, aim for the top of the surface to sit roughly 5-10 cm below your mattress top. This keeps your phone or book within easy reach without feeling like you are climbing up or down to grab them