An employee's gross salary differs substantially from the amount they take home on payday. Their employer (that's you!) has to withhold income tax, Medicare and Social Security taxes, and other deductions from their gross pay to write them a check for their net pay.
So what gross pay should you offer an employee to ensure they end up with the net pay you have in mind? Well, you could do a bunch of tricky calculations to add federal taxes and other deductions to the net amount . . . or you could use the free gross-up calculator on this page. You just need your employee's net pay and tax information to get started.