Compound Interest Calculator

This calculator starts with a principal balance, adds any monthly contribution you choose, and applies a return assumption across the selected number of years. It also considers the compounding frequency so the estimate can reflect how often growth is applied to the balance.

Each month, the balance is updated using the current estimate and then increased by the recurring contribution. That iterative approach makes the result more intuitive for people who save gradually rather than making only a one-time deposit. For retirement-specific planning, the retirement calculator gives a similarly practical view.

The future value is the projected ending balance based on the assumptions you entered. The total contributions figure shows how much money you added directly, while estimated growth isolates the portion attributed to the chosen return assumption.

That breakdown is helpful because it reminds you that long-term outcomes usually reflect both saving behavior and time, not just return assumptions. If the result is below your target, the savings goal calculator can help test a more concrete monthly contribution plan.

This tool uses a smooth hypothetical rate of return. Real markets do not move in a straight line, and actual investment results can vary materially from any steady-growth estimate. Fees, taxes, account types, contribution timing, and inflation are also outside the core calculation unless you model them separately.

Because of that, the output should be treated as an educational projection rather than an expected or guaranteed outcome. It does not provide financial, tax, legal, or investment advice, and it should not be used as a promise of future results.

Use this calculator when you want to explore how time, regular saving, and return assumptions interact. It is especially useful for early planning, comparing scenarios, or building intuition around why long time horizons matter.

It works well next to the retirement calculator for long-range planning and the savings goal calculator when you already have a target amount in mind.