Investment Calculator

Project a balance with deposits and withdrawals, then adjust it for inflation. An estimate, not investment advice.

Starting balance ($) *

Years *

Annual return (%) *

Inflation (%) *

Deposit ($)

Deposit schedule *

Withdrawal ($)

Withdrawal schedule *

Smart Tips

• A withdrawal is not the same as a lower deposit. The balance grows first, then the deposit is added, then the withdrawal is removed.

• Inflation does not change the nominal balance. It divides that balance by (1 + inflation) raised to the length of the term.

• An annual deposit or withdrawal happens in month 12, 24, and so on, after that month's growth.

• If a withdrawal is larger than the balance, the calculation stops instead of showing a negative account.

The Formula

Balance = Balance × (1 + rate ÷ 12) + deposit − withdrawal

Rate Nominal annual return
Divided by 12 each month

Deposit Cash added
Monthly, or once a year

Withdrawal Cash removed
After the deposit

Real Today's dollars
Ending balance ÷ (1 + inflation) ^ years

Investment growth is the ending balance minus the starting balance, minus deposits, plus withdrawals. That is the interest left after the cash you moved in and out. Compound interest on this site does not take withdrawals or an inflation adjustment.

Key Insights

Cash flow, not a lump sum

The ending balance depends on when money is added and removed, not only on the rate.

Nominal and real

The hero figure is the account in future dollars. The second figure divides it by cumulative inflation.

Flat cash amounts

Deposits and withdrawals stay at the numbers you type. They are not increased for inflation.

No tax drag

The rate you enter is used in full. Capital-gains tax, fees, and a changing market are outside this estimate.

Frequently Asked Questions

Compound interest on this site turns a lump sum and deposits into a future value. This page also removes withdrawals and restates the ending balance in today's dollars. The month-by-month order is growth, then deposit, then withdrawal.

After that month's growth. A monthly deposit is added every month. An annual deposit is added in month 12, 24, and so on. The withdrawal, if any, comes off after the deposit.

It is the ending balance divided by (1 + inflation rate) raised to years. Deposits and withdrawals are not inflated. A 0% inflation rate leaves the two balances equal.

Yes, down to just above −100% a year. A withdrawal that exceeds the balance after growth is rejected, because this page does not model a loan or a negative account.

No. The rate is applied in full. Fees, capital-gains tax, and dividends that are not part of the rate you typed are not calculated. This is an estimate, not investment or tax advice.

Investor.gov defines compound interest as interest paid on principal and on accumulated interest (Investor.gov, compound interest). This page applies that idea monthly: balance times (1 + annual rate ÷ 12), then the deposit, then the withdrawal. The inflation-adjusted result divides the ending balance by (1 + inflation) ^ years. No market feed is used.

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Ending balance

Enter values to calculate

In today's dollars

Investment growth

Note:This is an estimate. The return is a flat nominal rate, deposits and withdrawals do not rise with inflation, and taxes and fees are not removed. It is not investment advice.