All Calculators
Every FERSmath tool in one place. Pick a calculator below to get started — each one is free and runs entirely in your browser.
High-3 Average Salary Calculator
Calculate your FERS High-3 using OPM's 360-day rule. Enter your full GS grade and step history to find your highest 36-month window.
GS Salary History Lookup
Pick a grade, step, and locality area to see every year of available pay data and a chart of how the salary has grown.
TSP Fund Performance
Compare G, F, C, S, I, and Lifecycle fund share prices over any date range since May 2003 on an indexed performance chart.
TSP Monte Carlo Projection
Enter your current TSP balances and see a range of simulated future outcomes built from real historical fund returns, not a single assumed growth rate.
FERS Supplement Estimator
Estimate your FERS Supplement — the bridge payment you receive before age 62 that approximates your Social Security benefit.
TSP Projection Calculator
Project your Thrift Savings Plan balance at retirement based on contributions, agency match, and fund selection.
FERS Basic Annuity Calculator
Calculate your full FERS basic annuity including survivor benefit options and the impact of retiring before or after age 62.