A bed frame made for a queen-size mattress would not be able to support a mattress that was smaller because it is normally 6 to 7 inches wider and 5 inches longer than a full-size mattress. Potential harm could result from the inconsistency.
According to the Better Sleep Council, a regular queen-size mattress is roughly 60 inches wide by 80 inches long. A typical full-size mattress, in contrast, measures roughly 53 inches wide by 75 inches long.
A queen bed frame’s side rails would not be able to offer the full-sized mattress the solidity it needs to be kept in place. A full-sized mattress can only be supported by a queen bed frame with significant cross support, like one made of several wooden slats. But gaps would still remain between the mattress and the bed’s side.