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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.
There are some simple alterations that can be done, such as shortening or lengthening a waistline or sleeves, or grading in or out to a smaller or larger size in hip or waist. For more complex alterations, get yourself a good book detailing such changes. I use and can recommend "Fit for Real People", by Pati Palmer and Marta Alto. This book details alterations for many shapes and sizes with many illustrations and photos.