How to Figure the Belt Size for a Riding Lawnmower

Broken Belt or Cutting Belt for Immediate Replacement

• 1

  Cut though the belt with a utility knife if the belt wore but did not break on its own and you do not require the use of your mower before you can replace the belt. If the belt is already broken, do not cut it.

• 2

  Stretch the belt out with its flat side resting on a flat surface such as a table or garage floor. If the belt tries to roll up on its own, weight each end with something heavy.

• 3

  Place the end of a tailor's tape measure at one end of the belt and extend it to the other end. Take a measurement from the tape measure to determine the overall length of the belt.

Measure the Belt for Future Replacement

• 4

  Place the belt onto a flat surface, such as a table or garage floor, so the belt rests on its flat side and conforms to the shape of a circle.

• 5

  Place a mark on the inner edge of the belt with chalk to mark the starting and ending point of your measurement. Position the mark on the tip of the V-groove on the belt.

• 6

  Place one end of the tailor's tape measure on the mark, then extend the tape measure around the inside circumference of the circle until you reach the mark with the other end of the tape measure. Take your reading from the tape measure to determine the size of the belt.