How to measure for a kids bike to ensure the perfect fit?

To measure for a kids bike, have the child stand over the top tube with feet flat on the ground. There should be 1-2 inches of clearance between the top tube and the child's body. The child should be able to comfortably reach the handlebars and pedals. Adjust the seat height so the child's legs are slightly bent when the pedal is at its lowest point.