Last updated: 20 October 2026
Every calculator on Diving Finance uses a standard, published formula. This page shows each one in plain notation so you can check our numbers by hand or in a spreadsheet. Results are estimates; see the limits at the end.
EMI Calculator
We use the reducing-balance EMI formula that Indian banks use for home, car and personal loans:
EMI = P × r × (1 + r)^n / ((1 + r)^n − 1)
Here P is the loan amount, r is the monthly interest rate (annual rate ÷ 12 ÷ 100) and n is the tenure in months. Total interest is (EMI × n) − P. Example: ₹50 lakh at 8.5% for 20 years gives an EMI of about ₹43,391.
SIP Calculator
A SIP is treated as an annuity due, meaning each instalment is invested at the start of the month and earns returns for that month:
FV = M × [((1 + i)^n − 1) / i] × (1 + i)
M is the monthly SIP amount, i is the expected annual return ÷ 12 ÷ 100, and n is the number of months. The return you enter is an assumption. Real mutual fund returns go up and down and are not guaranteed.
Step Up SIP Calculator
With a step-up, the monthly amount rises by a fixed percentage once a year. We calculate month by month: for year y (starting at 1), the SIP amount is M × (1 + s)^(y − 1), where s is the yearly step-up rate. Each instalment is then grown to the end of the tenure:
FV = sum over every month k of [ SIP amount in month k × (1 + i)^(n − k + 1) ]
Here k runs from 1 to n, so the first instalment compounds for all n months and the last for one month.
Goal Based SIP Calculator
This works the SIP formula backwards. You enter a target amount (optionally inflated to future value at your chosen inflation rate), and we solve for the monthly SIP:
Future goal = Today's cost × (1 + inflation)^years M = Future goal × i / [((1 + i)^n − 1) × (1 + i)]
PPF Calculator
Public Provident Fund interest is compounded once a year. We assume the full yearly deposit is made by 5 April, so it earns interest for the whole year:
Balance at end of year = (Opening balance + Deposit for the year) × (1 + R)
R is the annual PPF rate. The default is 7.1% per year, as on 20 October 2026; please verify the current rate on the India Post or Ministry of Finance website, as the government reviews it every quarter. The calculator applies one rate for the whole term, while the real rate can change. Deposits are capped at ₹1.5 lakh a year, and the account runs 15 years.
FD Calculator
Most Indian banks compound fixed deposit interest quarterly. For a cumulative FD:
Maturity = P × (1 + R / 4)^(4 × t)
P is the deposit, R is the annual rate as a decimal and t is the tenure in years. Interest earned is Maturity − P. Results are before TDS and tax.
RD Calculator
For a recurring deposit, each monthly instalment is treated as its own small deposit, compounded quarterly from the month it is paid until maturity:
Maturity = sum over each instalment k of [ M × (1 + R / 4)^(4 × months remaining for k / 12) ]
M is the monthly instalment, and the first instalment has the full n months remaining. Banks may round interest each quarter, so small differences from your passbook are normal.
Home Loan Prepayment vs Investment Calculator
This compares two uses of the same lump sum or extra monthly amount:
- Prepay the loan. We cut the outstanding principal by the prepayment, keep the EMI the same, and recompute the remaining tenure month by month. Interest saved is the difference in total interest between the original and the new schedule.
- Invest instead. We grow the same money at your expected return (lump sum: P × (1 + i)^months; monthly amounts: the SIP formula above) over the remaining original tenure.
We then compare interest saved with the investment gain. As a rough guide, prepayment wins when your loan rate is higher than the after-tax return you can realistically expect. The calculator does not include tax benefits on home loan interest or principal, or tax on investment gains, unless the page says so. Those can shift the answer, so factor them in for your own case.
Limits of these calculators
- They assume a fixed rate for the whole tenure. Floating loan rates, small savings rates and market returns change.
- They ignore processing fees, prepayment charges, GST, stamp duty, TDS and income tax unless stated.
- Banks use their own rounding and day-count rules, so actual figures can differ by a few rupees or more.
- Expected returns for SIPs and investments are your assumptions, not forecasts.
Use the results to compare options, then confirm final numbers with your bank, fund house or a SEBI-registered adviser. Read our Disclaimer for more. Found a mismatch? Tell us on the contact page.