Retirement Planning Tools
Free calculators to model Roth conversions, Medicare costs, Social Security timing, and more. No login needed. Just plug in your numbers.
Coast FI Calculator
Find the age you could stop contributing to retirement accounts and still hit your number by retirement, growth alone.
Safe Withdrawal Rate Calculator
See how often a withdrawal rate actually survives across simulated markets, instead of taking the 4% rule as a flat answer.
Retirement Number Calculator
Quickly estimate the portfolio value you need to retire. Enter your spending goal, Social Security or pension income, and a safe withdrawal rate.
Roth Conversion Optimizer
See how much to convert each year to minimize lifetime taxes. Models your bracket, IRMAA thresholds, and ACA cliff simultaneously.
Roth Conversion Calculator
Find out how much you can convert this year before crossing into the next tax bracket, triggering IRMAA, or losing an ACA subsidy.
ACA Subsidy Calculator
Estimate your Affordable Care Act premium tax credit based on income, age, and household size. Critical for early retirees before Medicare.
IRMAA Calculator
Find out if your income triggers Medicare Part B or Part D surcharges, and by how much. Updated for current IRMAA brackets.
SEPP / 72(t) Calculator
Calculate substantially equal periodic payments for penalty-free IRA withdrawals before age 59½. Compares all three IRS-approved methods.
Tax Cliff Indicator
Visualize how close your income is to the ACA subsidy cliff, IRMAA tiers, NIIT threshold, and capital gains brackets, all at once.
Retirement Tax Planner
Full year-by-year tax projection through age 95. Combines Social Security, RMDs, Roth conversions, and spending into one integrated plan.
Want everything in one place?
ThunderHarbor connects all these tools into a single year-by-year plan: Roth conversions, Social Security timing, healthcare costs, and RMDs all computed together from your real numbers.
Build your free planFree plan included · Full optimizer suite with Premium ($47/year)