How can you estimate how much money you will have in the Thrift Savings Plan at the time you retire?  How can you estimate the amount of monthly income you will receive from the TSP?

The key word in both of the above questions is “estimate”, and the TSP calculators can help you with your estimation.  As with any estimate, the assumptions that you make will affect its accuracy as will the distance in time between when you make the estimate as will when the estimate is for.


The TSP has calculator features that can give you a hand in projecting TSP balances and the size of your TSP income stream on their website https://www.tsp.gov/PlanningTools/index.html.  These are not the most sophisticated calculators in the world, but they can give you an idea what the future might hold.  In the pre-retirement seminars that I do for federal agencies, I will go to the TSP website and do a quick demonstration of the first of the two calculators.  In this article, I will discuss the How Much Will My Savings Grow? calculator.  In another article I will cover the Retirement Income Calculator.

How Much Will My Savings Grow? is a calculator that can give you an idea of how much money you might have at a future date.  It asks you the following before it spits out its estimate:

  • Which retirement system you belong to.  If you choose FERS, it includes the government match in the calculations.
  • What growth you want to calculate.  You can choose: 1) current balance; 2) future contributions: or 3) both.
  • Your current TSP balance.  You can access your TSP account on the Thrift Savings Plan website to get the current amount.
  • How much longer you will contribute to the TSP.  Your answer must be in full years.
  • Your annual pay.
  • Your “pay schedule”; that is, how often you are paid (e.g., bi-weekly, monthly, etc.).
  • The percent of you annual pay that you would like to save.  It only takes whole percentages.  If you are contributing a fixed dollar amount to your
  • TSP, rather than selecting a percentage of salary, you will want to calculate (to the closest whole percent) the percentage of your salary that the fixed dollar amount represents.
  • The percentage of your expected annual pay increase.  This field accepts less than a whole percent so, for example, you could enter 1.6%.
  • The dollar amount that you plan to contribute in catch-up contributions (for those who are in their 50th year of birth or later).
  • The number of years before you begin withdrawing from your TSP account.  As with the question on how much longer you plan to contribute, the answer must be in full years.  If you are planning on withdrawing from your TSP immediately when you retire, this answer will be the same as the one you gave earlier.
  • The expected annual return.  You are called on to estimate the average rate of return over the period of time you calculate.  Your estimate will be applied evenly over the period of time.  If you estimated ten years at a 5% return, it would apply a 5% rate of return each year.  This is the “wild card” in this calculator, please be as realistic as you can in making this estimate.

I used the calculator making the following assumptions:

  • Contributing for five years
  • $200,000 current TSP balance.
  • $100,000 annual salary.
  • 18% contribution rate
  • 1.6% expected annual raises.
  • No catch-up contributions
  • Five years until I start withdrawals.
  • 5% annual return.

I ended up with a balance of $389,398.30 – close to double the amount that I started with.  This was due to:

  • $200,000 already in the account.
  • $55,256.31 of growth of that $200,000 over five years at 5%.
  • $118,739.40 of future contributions.
  • $15,402.59 of growth of the future contributions.

Obviously, these are made-up numbers.  Why don’t you try the How Much Will My Savings Grow? calculator and find out how much your savings will grow.