Measure the length of the wall using the tape measure. Make a note of this figure.
Measure the width of the wall using the tape measure. Make a note of this figure.
Measure the height of the wall using the tape measure. Make a note of this figure.
Multiply the three previous attained figures together. The product of these will be the volume of the wall.
Multiply the volume of the wall by the density of the type of stone the wall is made of. The density of granite is around 0.17 pounds per cubic foot. This gives you the mass of the wall. Make a note of this value.
Multiply the mass of the wall noted above by the acceleration due to gravity. This is around 32.17 feet per second squared. This gives you the load of the wall.