Understanding your result
Maturity combines all monthly deposits with estimated interest. Early installments earn for longer than later ones. The effective annual yield describes the quoted rate with quarterly reinvestment; it is not interest divided by the total deposits.
If the entire amount is available on the opening date, compare a single deposit using the Fixed Deposit Calculator instead of treating it as monthly installments.
The formula
The annual rate is a decimal and n is the number of monthly installments. The calculation advances one equal month at a time using the cube root of the quarterly factor. At zero interest, maturity is simply the installment multiplied by the number of months.
An installment timing check
If you deposit 1,000 each month for two years at zero interest, the balance is 24,000. With a positive rate, start-of-month deposits earn one extra month of interest compared with otherwise identical end-of-month deposits.
How to use this calculator
- Enter the installment and the annual rate quoted for your recurring deposit.
- Choose the full-year term and when installments are paid.
- Inspect individual years to separate your own deposits from gross interest.
Quarterly compounding with monthly installments
A recurring deposit has monthly cash flows even when the quoted interest compounds quarterly. Applying a simple annual rate to the total deposits overstates interest because most of that money was not present on the opening date. Each installment needs its own remaining earning period.
This model converts quarterly growth into equal monthly factors. Banks may instead use actual payment dates and actual-day calculations, including leap years and broken periods. Missed installments, delayed payments, penalties, and premature closure can therefore change the amount finally paid.
Assumptions & limitations
What this calculation assumes
- The installment and quoted rate stay fixed.
- Every deposit is made on time.
- A year contains twelve equal modeled months.
What to keep in mind
- This is not an exact bank maturity quote.
- No tax, withholding, late fees, or withdrawal penalties are deducted.
Common questions
Why is this different from the SIP calculator?
The RD estimate converts a quarterly-compounded deposit rate to a monthly factor. The SIP model divides a nominal annual return directly by twelve. Their rate conventions are different.
Can I model an irregular deposit schedule?
No. Use this result only for equal monthly installments. Actual irregular payments require a dated cash-flow calculation.