• Planning for retirement can be just as stressful as making it up the corporate ladder in one piece. Several retirement calculation methods exist to help you determine the finances necessary for you to retire in the manner that suits you best. When in doubt about your financial future, always contact a licensed financial planner to answer your questions.
  
  

Percentage of Working Salary

• According to financial planning website Smart About Money, at least 80 percent of your annual working salary is necessary in order to retire in the style you've become accustomed to over your working life. Calculating this salary percentage of the years you expect to be retired is a good method of determining the lump sum of money you need to retire comfortably. For example, if $60,000 is 80 percent of your annual salary and you anticipate being retired for 20 years you will need $1.2 million to reach your goal.
  
  

Living Off The Interest

• Living off the interest is a method of calculating retirement needs through the growth of your finances through successful investing. This method involves establishing a financial figure you anticipate needing as your annual retirement salary and anticipating the interest rate of your financial investments necessary to meet that goal. For example, if you plan to retire on a monthly income of $4,000 at 8 percent interest, you will need to accumulate about $3.1 million, according to the retirement planning website Simple Joe.
  
  

Realistic Retirement Goals

• A third method of planning for retirement determines how much you need to invest monthly in order to live well when retired and leave a little behind for your survivors. This method calculates your living allowance under the assumption that you will either use your retirement fund entirely or leave whatever is left to family. It is also the cheapest but requires the largest time investment. For example, if you plan to be retired for 25 years on a monthly retirement salary of $4,000 you must invest about $900 a month in a retirement account that earns an average of 12 percent interest over a period of 40 working years, and 8 percent once you're retired according to investment firm ING.