sleep with a partner, try it out together.
am i buying the right size?
the general rule of thumb is to buy the biggest bed you can fit into your room. the larger the bed, the more room you (and your sleeping partner) have to move during the night without disturbing each other.
is the mattress long enough?
taller people need more room to stretch out comfortably, so it's important to check that the mattress is longer than the tallest sleeper. 