You can judge the number of ties you need for a project by considering how many ties make up a yard of fabric.  The average tie is about 3" wide at the narrow end and at least 50" long.  That means that it takes about 12 ties to equal a yard of fabric.  And that doesn't allow for the extra you have at the wide end, where you can cut larger pieces.  The fronts and back of a jacket require at least 1 3/4 yards of fabric, depending on size and length.  Sleeves take about 3/4 yard.  Mixing in a coordinating fabric reduces the number of ties needed.