Determine what size belt your machine requires: 

Step 1 - Remove old belt if still attached to machine.

Step 2 - Adjust motor to center position. Most sewing machine motors have a bolt or screw that holds the motor in place. When this bolt or screw is loosened, the motor will move in two directions. Loosen this screw and move the motor to center position and re-tighten the bolt or screw. The reason for this step is so that you will have about 1/2" worth of adjustment for the new belt.

Step 3 - Take a piece of non-stretchable string and run it around the machine's hand wheel and motor pulley. Be sure that the string is inside of the belt groove of the hand wheel and pulley.

Step 4 - Cut the string so that two ends meet. This will tell you what size of belt you will need.

Step 5 - Remove the string from the machine and lay it flat and straight on a table. Using a measuring device, measure the complete length of the cut string. Now you will know what size of belt to order. For example, if the string measures 16 1/2" long, then you will need a 16 1/2" belt. Once the new belt has arrived, you simply loosen the bolt or screw that is holding the motor in place. Then attach the belt around the hand wheel and pulley. Make sure the belt is inside the belt grooves. You may have to lift or adjust the motor slightly in order to get a good fit. Once the belt is in place, simply apply a little down pressure on the motor while tightening the bolt or screw. The belt should be tight enough so that it doesn't slip, but not too tight so that it puts strain on the motor. Loosen the motor bolt/screw and adjust the belt tension as needed.