Source: Martha Stewart Living, August 2006
Cover up with a breezy beach wrap made from a favorite fabric.
Fabric (see steps to determine amount)
Measure your body from waist to ankle. Then measure around your hips, multiply that number by 2, and add 2 inches to that.
Cut fabric so that one long side falls along the selvage (we used Indian cotton cut from a 45-inch bolt).
With fabric right side down, double-hem each short side 1/2 inch (pressing after each fold).
To make the waistband: Double-hem the unfinished, long side of the fabric 1 1/2 inches (pressing after each fold).
Leave the selvage edge as is. To add ties: Tuck a 24-inch-long piece of ribbon (ours was 5/8-inch-wide twill) in each end of the waistband, and stitch in place, as pictured.