13 distance is the minimum you should aim for.
Standard over the stove microwave size.
The following dimensions are typical for over the range microwaves based on a study of popular models available from major manufacturers.
Typical dimensions over the counter microwave 24 x 14 x 16 width height depth and 1 5 cubic feet capacity.
Typical over the range microwave under 30 kitchen cabinet might have an actual width 29 1 2 29 3 4 29 7 8 29 15 16 or precise 30.
Because they need to fit into the space above a standard cooktop over the range microwaves offer less variation than countertop models in terms of size.
Note that they are organized by capacity.
Over the range microwave average size and dimensions the typical external microwave dimensions of an over the range microwave are 30 inches wide 15 inches tall and 16 inches deep although they can vary as they need to fit into specific cabinet spaces.
Therefore considering the earlier measurements discussed in point 1 above you will have about 13 of distance left between the cooktop and the bottom of the otr microwave oven.
The more the merrier.
Typical over the range microwave designs are 16 inches high by 30 inches wide by 15 inches deep.
Their heights range from 12 to 16 inches.
These units range in width from 21 to 29 inches.