Determine Your Hat Size
Using a string or a tailor's measuring tape, measure around your head 1/2" above your ears. Your hat size is determined by figuring the average diameter of your head. To find this, divide the number of inches you've measured by 3.14159. The resulting number is your hat size. Otherwise, just use this handy chart.
How To Determine Your Belt Size
Your belt size is normally your pant size plus one size. For example, if you wear a 28 inch pant, you should buy a 30 inch belt.
How To Determine Your Ladies Jacket Size
Using a tailors tape measure or a string, measure your bust, waist and hip sizes in order to determine which size jacket would best fit you.