The ideal height of a mattress from the floor can vary based on personal preferences and factors such as the height of the bed frame and your body type. In general, the height of the mattress from the floor should allow you to comfortably get in and out of bed without having to strain or jump.
A typical height for a mattress from the floor is between 20 to 26 inches. This height allows most people to easily get in and out of bed without difficulty. However, some people may prefer a higher or lower height based on their individual needs and preferences.
If you have a platform bed or a low-profile bed frame, a lower mattress height may be more suitable. (Opposite is true, most people would pick a thicker mattress). If you have a taller bed frame or prefer a higher bed height, a thicker mattress or the addition of a box spring or foundation may be necessary to achieve the desired height. (opposite is true again). Ultimately, the ideal height of a mattress from the floor will depend on your individual needs and the configuration of your bed.
(it's important to consider the total height from the floor of your mattress vis-à-vis the height of your headboard and footboard, in other words, it has to look right proportionally)