How to Calculate Your Chinese zodiac sign? Use the following three steps to calculate your sign. 1. Your Birth Year + 9 = N. 2. Divide N by 12 and read about the remainder. If you use an electronic math calculator, after you get the result, make the decimal multiplied by 12 to get the remainder. If remainder is indivisible, you need to do decimals to round up and round down numbers. 3.