How this calculation works
Monthly debt = max(0, previous debt × (1 + annual debt rate ÷ 12) − payment)
Net worth = invested assets + other assets − debt
Rates in the formula are decimals. Deposits and debt payments occur at month-end. Other assets stay constant. When a debt is repaid, its payment is not automatically redirected into investments. Inflation-adjusted results divide future net worth by (1 + inflation) raised to the number of years. Taxes, fees and changing income are not modeled.
A worked example
At zero growth, $100,000 of investments plus $500 each month becomes $220,000 after 20 years. Adding $250,000 of unchanged other assets and subtracting the remaining modeled debt gives the projected net worth.
Common questions
Why are there three return scenarios?
The lower and higher scenarios change the investment return by two percentage points. They are sensitivity checks, not a probability range.
Can debt increase?
Yes. If monthly interest exceeds the payment, the modeled debt grows. Review the debt column rather than assuming every payment pays down principal.
Go a little deeper.
Read the supporting guide for definitions, examples and common mistakes.
Read the guide ↗Educational tool, not individualized financial, investment or tax advice. Estimates depend on your inputs and do not guarantee future results.
Background: Investor.gov compound interest calculator. NetWorthXI’s implementation and stated assumptions determine these results.