How this calculator works
- Step 1Deposit by the 5th₹1,50,000.00Money in the account by the close of the 5th counts for that month.
- Step 2Interest each month0.59%One twelfth of the yearly rate, on that month’s lowest balance after the 5th.
- Step 3Credit on 31 March₹10,650.00The year’s monthly interest is added in one credit and earns interest from April.
PPF, the Public Provident Fund, is a government small-savings account. The Public Provident Fund Scheme, 2019 says interest is worked out each month on the lowest balance between the close of the 5th day and the end of the month.
That monthly interest is not added each month. It is credited once, at the end of the financial year on 31 March. Interest therefore compounds once a year, and the date your money arrives changes how many months it earns.
The rate is a user input. It defaults to 7.1%, the rate listed for 1 October to 31 December 2026. The same rate is applied to every year, because future quarterly rates are not known.
Worked example: the yearly maximum every April
- Interest in a year
I = r × (opening balance + deposit × k)- Balance after n years
B = A × (1 + r × k) × [(1 + r)^n − 1] / r
- Adeposit each financial year ₹1,50,000.00
- ryearly rate as a decimal 7.1%
- kshare of the year the deposit earns 12 of 12 months
- nfinancial years 15
- Year 1 interest on the April deposit₹10,650.00
- Balance on 31 March, year 1₹1,60,650.00
- Year 2 interest on balance plus deposit₹22,056.15
- Total deposited over 15 years₹22,50,000.00
- Total interest₹18,18,209.22
- Estimated balance at maturity₹40,68,209.22
A deposit on or before 5 April counts for all 12 months, so k is 1. The year-by-year table in the calculator repeats this sum for every year and agrees with the formula.
HDFC Bank’s published PPF calculator shows the same plan at ₹40,68,209 when rounded to the rupee. We use it as an outside check on the method.
The 5th of the month changes the answer
- Deposits
- Interest
A deposit made on the 6th misses that month, because the month’s lowest balance was set before it arrived. It starts earning from the next month.
Monthly deposits put less money to work early in each year. The monthly options here split the yearly total into 12 equal parts. Real deposits must be in multiples of ₹50.00.
After 15 years: extend or stop
- Extend with deposits₹66,58,288.17Keep paying the same amount each year for five more years.
- Extend without deposits₹57,32,586.73The 15-year balance keeps earning interest; no new money goes in.
- Close at maturity₹40,68,209.22Balance at the end of the 15th financial year.
The scheme lets you extend in blocks of five years. You choose by applying within one year of maturity. Without that application, new deposits are refunded without interest, though the balance still earns interest.
The account matures 15 complete financial years after the end of the year you opened it. Year 1 in this calculator is the first full financial year, so an opening part-year is not shown.
Reading the result and its limits
The result is an estimate at one fixed rate; the actual balance depends on every future quarterly rate and the dates your deposits are credited.
With a zero rate, the balance is simply your deposits: ₹22,50,000.00 over 15 years. Everything above that in the result is interest, which depends on the rate entered.
The calculator does not round interest to the rupee. Post offices and banks may round each year’s credit, so a passbook can differ by a few rupees. Loans, partial withdrawals, missed years and premature closure are not modelled.
Other government-backed schemes have different terms. Compare the five-year NSC calculator, the SSY calculator for a daughter’s account, or the market-linked NPS calculator. The inflation calculator shows what a 15-year maturity buys in today’s money.
Common mistakes
Mistake: Depositing on the 6th or later and expecting interest for that month.
Instead: Make sure the credit reaches the account by the close of the 5th.
Mistake: Assuming today’s rate will apply for all 15 years.
Instead: Treat the rate as an assumption and test a lower and a higher one.
Mistake: Paying more than ₹1,50,000.00 in a financial year across your own and a minor’s account.
Instead: Keep the combined total within the yearly limit; excess deposits earn no interest.
Mistake: Expecting interest to be added to the balance every month.
Instead: Interest is worked out monthly but credited once, on 31 March.
Methodology and sources
Tests compare the formula with an independent day-by-day simulation of the lowest-balance rule and with a bank’s published figure.
The deposit limits, term, extension blocks and interest rule come from the Public Provident Fund Scheme, 2019 on the National Savings Institute site. The rate comes from India Post’s savings-scheme page and the NSI rate history.
Interest and tax treatment can change with new notifications. This page will be reviewed when the next quarterly rate is announced. Source links, the review date and the financial disclaimer follow. Read how we test our calculators, or browse more money calculators.