Originally Posted by mstateglfr

In not aware of it being possible since stack and reach are direct measurements.

put your bike against a wall with the rear tire touching a wall in back, and make sure the bike is vertical(vs leaning). A strap around the front tire and down tube help keep it from rolling.

measure from the floor vertically to the center of the bottom bracket.
now measure from the floor vertically to the middle point of the top of the head tube.
Subtract small # from big # and that is stack.

measure from the back wall to the center of your bottom bracket.
now measure from the back wall to the center of the top of the head tube.
subtract small # from big # and that is reach.

this is frame stack and frame reach.

another way is to shove the bike into a corner so both tires touch a wall and a handlebar touches a wall. It helps ensure the bike stays still and vertical and gives you the same measurements.