Savings Calculator - Maturity Amount | Financial Calculator
Free savings calculator to estimate your maturity amount after tax. Enter monthly deposit, interest rate, and period to see your after-tax returns.
How installment savings interest works here
The calculator assumes one deposit at the beginning of every month, each earning interest from its deposit month through maturity at the monthly rate (annual ÷ 12). Interest in the default mode is simple — it does not compound — which mirrors how most fixed-term installment savings products quote their rates. The optional compound mode shows how the same plan would grow if interest were reinvested monthly instead.
Worked example at a hypothetical rate
Saving $500 per month at a 4% annual rate for 24 months: deposits total $12,000, pre-tax interest comes to $500.00, the English edition's 15% interest tax deducts $75.00, and the after-tax maturity amount is $12,425.00. The same plan in compound mode would earn slightly more, since each month's interest starts earning interest of its own. Figures are informational, not a rate quote.
How to Use
- Monthly Deposit — Enter the fixed amount you plan to put away each month, for example $500
- Annual Interest Rate — Enter the account's annual rate (%); internally the calculator works with the monthly rate, annual ÷ 12
- Deposit Period — Set the duration in years or months — a 2-year plan becomes 24 monthly deposits
- Interest Mode — Keep the default simple mode used by most installment-savings products, or switch to monthly compounding
- Calculate — Click Calculate to see total deposits, pre-tax interest, the tax deduction, and the after-tax maturity amount
- Compare Products — Adjust the rate or period and recalculate to compare offers; your inputs can be shared via the page URL
FAQ
What tax rate does the calculator apply to interest?
The English edition applies a 15% interest income tax; each language edition uses a typical local rate (the Korean edition, for example, applies 15.4%). Tax = pre-tax interest × rate, and the maturity amount = total deposits + interest − tax.
How do I calculate tax-exempt savings?
Tax-exempt accounts pay no income tax on interest. The pre-tax interest shown equals the actual interest received on a tax-exempt account.
How is savings interest calculated?
Each monthly deposit earns interest from deposit date to maturity. The formula is M × r × n(n+1)/2, where the first month's deposit earns the most interest.
What is the difference between simple and compound mode?
In the default simple mode each deposit earns flat monthly interest until maturity, summing to M × r × n(n+1) ÷ 2. In compound mode deposits follow the future-value-of-annuity formula M × ((1+r)^n − 1) ÷ r, so earned interest itself keeps earning.
Which deposit earns the most interest?
The first one. With one deposit at the start of each month, the first deposit in a 24-month plan earns interest for all 24 months while the final deposit earns it for just one — that is exactly what the n(n+1) ÷ 2 term adds up.
Why might my bank's quoted maturity differ slightly?
The calculator keeps full precision internally and rounds only the displayed result to two decimals. Banks may round monthly, credit interest on business days, or apply promotional tiers, so real statements can differ by small amounts.