To determine Stabilizer (Sway) Bar diameter, measure the bar next to the bushing (toward the center of the vehicle), utilizing one of the methods below.

Use a Digital calliper or micrometer for a precise reading

Use an open end wrench that fits snug around the bar, or tighten an adjustable wrench around the bar, and then measure the span opening

Wrap a piece of non-stretchable tape (like masking tape) around the bar to get the circumference. Circumference divided by Pi (3.14) = Diameter. In the example below, the tape measured 3 5/8". 3 5/8 = 29/8 = 3.63 inches. Diameter = 3.63/3.14 = 1.15 inches.