1. Take a tape measure to your favorite fitting sweater and measure across the widest part. Multiply the number by two. So for example If my favorite sweater measures 20 inches across the bust, then I need to knit the 40″ bust size. The magic of this method is that your favorite sweater already has the exact amount of ease that you prefer.
2. Take a tape measure and measure around the widest part of your bust. Add two inches. My bust measures 40″ so I knit the 42″ version of the sweater and I absolutely adore the fit. The Mariposa Tee has zero ease, so if you are lumpy and bumpy like I am, go up one size!