Wear well-fitting pants or shorts, or measure directly on bare legs
Stand straight with feet about 6 inches apart
Use a soft measuring tape
Measure from the crotch seam down the inside of the leg to the bottom of the ankle
Keep the tape snug but not tight
Record the length in inches or centimeters
For accuracy, have someone help you measure
Compare the measurement to the inseam listed on pants labels
Repeat the measurement on both legs if needed and use the longer one