Savings Calculator

Solve for a future balance, the regular deposit, or the time to a goal. An estimate, not savings advice.

Solve for *

Starting balance ($) *

Deposit each period ($) *

Annual rate (%) *

Deposit schedule *

Years *

Smart Tips

• Pick future value when you know the deposit. Pick the deposit when you know the goal and the time. Pick time when you know both dollars.

• The deposit and the compounding share one schedule. A monthly deposit uses a monthly rate.

• A deposit is added at the end of the period, so it does not earn interest in the period it is deposited.

• The compound-interest calculator only solves a future value, and it treats extra deposits as monthly even when compounding is not monthly.

The Formula

Future = Present × (1 + r) ^ n + Deposit × ((1 + r) ^ n − 1) ÷ r

r Rate per period
Annual rate ÷ periods per year

n Number of deposits
Years × periods per year

Deposit Solved the other way
(Future − present × (1 + r) ^ n) × r ÷ ((1 + r) ^ n − 1)

Time Solved the other way
ln((future + deposit ÷ r) ÷ (present + deposit ÷ r)) ÷ ln(1 + r)

Investor.gov defines compound interest as interest paid on principal and on accumulated interest. It does not print this three-way savings solve. The identities above are the ordinary-annuity forms used on this page. At a zero rate, future value is the starting balance plus deposit times the number of periods.

Key Insights

Three unknowns, one at a time

You choose which of the balance, the deposit, or the time is missing.

Same period for both

A weekly deposit compounds weekly. It is not converted into a monthly side calculation.

End of the period

Money you add does not earn interest until the next period.

A reached goal stops the solve

If the starting balance already covers the future balance, time is not a positive number.

Frequently Asked Questions

The compound-interest calculator solves only a future value. Extra deposits there are monthly, whatever compounding frequency you pick. This page can solve the future balance, the deposit, or the time, and the deposit uses the same periods as the rate.

At the end of the period. A deposit made with the last payment of the year does not earn that year's rate. This is an ordinary annuity, not an annuity due.

The future balance is the starting balance plus every deposit, with no growth. Solving for the deposit divides the gap by the number of periods. Solving for time does the same. A zero rate and a zero deposit cannot close a gap.

No. If the starting balance already grows past the goal, the page says the goal is already met. It does not solve for a withdrawal.

No. The deposit you enter stays the same every period. Taxes and fees are not taken out. This is an estimate, not savings advice.

Investor.gov's compound-interest glossary says compound interest is interest paid on principal and on accumulated interest. It does not give the deposit or time formulas. Those ordinary-annuity identities are stated on this page. No market rate is used.

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Note:This is an estimate, not savings or investment advice. The rate stays flat, deposits are not indexed to inflation, and taxes are not subtracted. A bank may credit interest on a different day than the end of the period used here.