If you allow too much tax to be withheld, you get a refund. You can determine how much is tax is taken out of your pay by the number of allowances you claim on your W-4. The W-4 has a worksheet to help you figure out how many personal allowances to take.
Step 5: Predict your next period. Now that we know how long your period cycle is, we can just use it to count the days to predict your next period. My period cycle is 28 days so if I count 28 days from February 10, that's when my next period should come.
Such a calculator helps you estimate when your menstruation will occur. It will give you the estimated starting dates for the next 12 periods, over the course of the next year. All you have to do is to enter the starting date of your last period and the average length of your period cycle.