To estimate your monthly TSP annuity payment you can use

an online calculator or download a worksheet.

Use the  href="https://www.tsp.gov/planningtools/annuities/annuityCalc_select.shtml"

target=_blank>TSP Annuity Calculator  on the Web site to estimate

what your monthly annuity payments might be.  The amount of your monthly

annuity payments depends to a large degree on the size of your TSP account

balance (or the portion of your account that you intend to use to purchase the

annuity).  In addition, the type of annuity you choose, your age (and your

joint annuitant's age in the case of a joint life annuity), and the interest

rate index at the time that the TSP purchases your annuity, affect the monthly

amount that you will receive.

If you prefer to do your own calculations, you can download the

TSP Annuity Worksheet (available at:   href="https://www.tsp.gov/PDF/formspubs/worksheet.pdf">https://www.tsp.gov/PDF/formspubs/worksheet.pdf)  with

the monthly annuity factor tables and interest adjustment factors to estimate

your payment under various annuity options.