ReckonBoxHow the PPF calculator works
A PPF calculator projects a Public Provident Fund to maturity: it takes your yearly or monthly deposit, the tenure, and the interest rate, and returns the maturity value, the total interest, and a year-by-year chart. The Public Provident Fund is a fixed-rate central-government savings scheme, so the rate is the same at every bank and the post office. As of the October to December 2026 quarter it pays 7.1% a year, compounded annually, a rate unchanged since 1 April 2020.
Feed it the standard case and the number falls out. Depositing the full ₹1,50,000 a year for 15 years at 7.1% grows to about ₹40.68 lakh, of which ₹18.18 lakh is interest on ₹22.5 lakh invested. The tool also reports the 80C tax the deposit saves, and it takes an existing balance so you can project an account you already hold.
How PPF interest is actually calculated
PPF interest is paid on the lowest balance in your account between the 5th and the last day of each month, then compounded annually and credited on 31 March. That one rule is the reason deposit timing matters, and it's the rule almost every calculator quietly ignores. A deposit reaching the account on or before the 5th earns that month's interest; a deposit after the 5th earns nothing for that month.
This calculator simulates all 12 monthly minimum balances instead of approximating a year of deposits as a single lump sum. The difference is real money. A single ₹1.5 lakh deposit in April earns interest on the whole amount for all 12 months, while ₹12,500 paid monthly sits in the account for only part of the year, so it earns less. Over 15 years at 7.1%, the monthly plan matures at about ₹39.45 lakh against the yearly lump sum's ₹40.68 lakh, a gap of roughly ₹1.24 lakh on the same ₹22.5 lakh invested.
Worth keeping that gap in proportion. It's about 3% of the final corpus spread over 15 years, so the April scramble is worth something without being the difference between a comfortable retirement and a thin one. Miss the 5th on a monthly deposit and you forfeit one month's interest on that single installment, which is a rounding error next to the yearly-versus-monthly choice itself.
The maturity formula
For a yearly deposit made at the start of the financial year, PPF maturity is the future value of an annuity due: M = P x [((1 + i)^n - 1) / i] x (1 + i), where P is the annual deposit, i the annual rate as a decimal, and n the number of years. The trailing (1 + i) carries the whole argument, because the April deposit earns interest in the same year it's paid.
Here's where the published calculators come apart. Every ranked PPF calculator we checked prints the formula without that trailing term, as F = P[({(1+i)^n}-1)/i], which is the ordinary annuity and assumes each deposit lands at the end of its year. They then display a maturity figure the printed formula cannot produce.
| Deposit | Their printed formula gives | The figure they display |
|---|---|---|
| ₹1,50,000 a year, 15 years, 7.1% | ₹37,98,515 | ₹40,68,209 |
| ₹1,00,000 a year, 15 years, 7.1% | ₹25,32,343 | ₹27,12,139 |
That's a ₹2,69,695 discrepancy on the headline example, about 7% of the corpus. The displayed numbers are right and the formula beside them is wrong.
The mismatch isn't academic pedantry, because those two formulas are exactly the two ends of the deposit-timing question. An annuity due is a deposit on 5 April, earning all 12 months. An ordinary annuity is a deposit on 31 March, earning nothing that year. Several pages describe the 5th-of-the-month rule in their own prose and still print the formula that contradicts the number sitting next to it.
For monthly deposits the closed form overstates the return either way, since it credits a full year of interest to money that arrived across the year. Simulating the 12 monthly balances, as this tool does, is what keeps the monthly and yearly answers honest.
The year-by-year chart
Watching the balance build is where the compounding becomes obvious. On the default ₹1.5 lakh yearly deposit, the first year earns ₹10,650 of interest, but by the final year the account is throwing off about ₹2.7 lakh of interest annually, more than the ₹1.5 lakh you put in.
| Year | Deposit | Interest that year | Balance |
|---|---|---|---|
| 1 | ₹1,50,000 | ₹10,650 | ₹1,60,650 |
| 8 | ₹1,50,000 | ₹1,09,661 | ₹16,54,185 |
| 15 | ₹1,50,000 | ₹2,69,695 | ₹40,68,209 |
By year 15, interest is earning far more than the fresh deposit, which is compounding doing the heavy lifting. The full table in the tool shows all 15 rows, and extends further if you set a longer tenure.
PPF tax benefits (EEE)
PPF is fully exempt-exempt-exempt: the deposit earns a Section 80C deduction, the interest is tax-free, and the maturity amount is tax-free. The 80C deduction covers up to ₹1.5 lakh of deposit a year, and this calculator turns it into a rupee figure at your slab. A 30% taxpayer depositing the full ₹1.5 lakh saves ₹46,800 in tax each year including the 4% cess, which is ₹7.02 lakh across the 15-year term on top of the interest.
One catch decides whether that deduction is worth anything. The 80C benefit is available only under the old tax regime, so a saver on the new regime, now the default, gets no upfront deduction, though the interest and maturity stay tax-free either way. Set the calculator to the new regime and the tax-saved figure drops to zero.
Deposit limits and the 15-year lock-in
The limits are short enough to hold in your head:
- ₹500 minimum a year, and an account that takes nothing in a year goes dormant.
- ₹1,50,000 maximum a year, in a lump sum or up to 12 installments.
- Anything above ₹1.5 lakh earns no interest and no deduction, so the calculator caps the yearly amount there.
The lock-in runs 15 years counted from the end of the financial year you opened in, not from the day you opened. An account started in January 2026 therefore matures in March 2041, not January 2041.
That counting convention quietly costs you up to a year, and it's the reason two people who opened accounts three months apart can mature in the same month.
Withdrawal, premature closure and the loan
Partial withdrawal from a PPF account is allowed from the 7th financial year, once per year, capped at 50% of the lower of two balances: the one at the end of the 4th preceding year and the one at the end of the immediately preceding year. The account stays open and keeps compounding.
Ask the internet when you can take money out and you'll get four different answers. Among the ranked pages we checked, some say the 7th year, some say the 6th, and several say after 5 years; one publisher gives the 7th year on its calculator page and after 5 years on two of its own explainer pages.
The disagreement has a cause. Two separate facilities get collapsed into one line:
| Facility | From when | What it costs you |
|---|---|---|
| Partial withdrawal | 7th financial year | Nothing; account stays open |
| Premature closure | After 5 complete financial years | Interest recomputed 1% lower for the account's whole life |
| Loan against balance | 3rd to 6th financial year | Interest at the PPF rate plus 1% |
Premature closure is the "after 5 years" everyone half-remembers, and it isn't a withdrawal at all. It shuts the account, it's permitted only on specified grounds (serious illness, higher education, or a change of residency status), and the 1% penalty applies retroactively across every year the account ran.
The loan deserves its own correction, because "25% of your balance" is how it's usually described and every part of that is load-bearing:
- The cap is 25% of the balance at the end of the second preceding financial year, which in year 3 is a far smaller number than the account currently holds.
- It carries interest at the PPF rate plus 1%, a spread the 2019 scheme cut from 2%.
- Repayment runs 36 months.
- Anything still outstanding after that is charged at the PPF rate plus 6%.
So it is a loan, priced like one, and not an early withdrawal by another name.
What happens at 15 years
Three doors open at maturity:
- Take the whole balance out tax-free and close the account.
- Extend for five years with fresh deposits, which needs Form H.
- Extend for five years with no further deposits, which happens by default.
Extensions repeat in 5-year blocks indefinitely, which is why this calculator accepts tenures of 20, 25 years and beyond.
Extending with contributions requires Form H, filed within one year of the maturity date. Miss that window and the account defaults to the no-contribution mode for the entire block, with deposits blocked until the next one begins. Money paid into a matured account with no Form H on file is treated as irregular and earns no interest at all, which is the sharpest trap in the scheme and appears on almost no calculator page.
The withdrawal rules then invert in a way most people guess backwards. In a with-contribution extension you may withdraw up to 60% of the balance held when the block started, spread across the five years, one withdrawal a financial year. In a without-contribution extension you may take one withdrawal a financial year of any amount. Stopping your deposits buys you more access to the money, not less.
PPF or ELSS for your 80C
Both PPF and ELSS earn the same Section 80C deduction, but they sit at opposite ends of the risk scale, and the choice comes down to what you can hold.
| Feature | PPF | ELSS |
|---|---|---|
| Return | 7.1% fixed, set by the government | Market-linked equity, not guaranteed |
| Lock-in | 15 years | 3 years |
| Risk | Capital guaranteed | Market risk |
| Tax on gains | Fully tax-free (EEE) | 12.5% LTCG above ₹1.25 lakh |
| 80C deduction | Up to ₹1.5 lakh (old regime) | Up to ₹1.5 lakh (old regime) |
PPF trades a lower, certain return for zero risk and a long lock-in; the ELSS calculator models the equity side of the same 80C decision. Which suits you depends on your horizon and your tolerance for market swings, and not on a rule of thumb.
What this does not promise
The 7.1% rate isn't fixed for the life of your account, and the way it moves is worth understanding. PPF is a floating-rate scheme: when the government resets the quarterly rate, the new rate applies to your entire accumulated balance, including every rupee deposited years earlier. Several sibling schemes work the opposite way. NSC, KVP, SCSS, Post Office MIS and the 5-year Time Deposit all lock the rate on the day you open, and hold it for the full term.
That distinction is why a 15-year PPF projection at today's rate is a planning estimate and never a quote. A rate cut in year 9 doesn't just slow new deposits, it reprices the whole corpus. The tool holds the rate you enter flat across the tenure, which is the standard convention, so treat the output as an illustration pinned to today's rate. PPF returns and rules are set by the government and this is not investment advice, so for your own plan a SEBI-registered adviser can weigh PPF against your other goals. To compare it with a market-linked option, the SIP calculator projects an equity investment at an assumed return.
Frequently asked questions
What is a PPF calculator? A PPF calculator estimates the maturity value of a Public Provident Fund from your deposit, the tenure, and the interest rate, and shows the year-by-year growth. It also reports the total interest earned and, here, the 80C tax the deposit saves at your slab.
What is the current PPF interest rate? The PPF interest rate is 7.1% per annum for the October to December 2026 quarter, compounded annually. The government sets it every quarter, and it has stayed at 7.1% since 1 April 2020. The rate is the same at every bank and the post office, since it is a central-government scheme.
How is PPF interest calculated? PPF interest is calculated on the lowest balance in your account between the 5th and the last day of each month, then compounded annually and credited on 31 March. Because of this, a deposit made on or before the 5th earns that month's interest, and a deposit after the 5th does not.
Is it better to invest in PPF yearly or monthly? A single lump sum deposited early in April earns more than the same amount spread across the year, because PPF pays on the monthly minimum balance. Depositing ₹1.5 lakh in April gives about ₹40.68 lakh after 15 years at 7.1%, while ₹12,500 a month gives about ₹39.45 lakh, a difference of roughly ₹1.24 lakh for the same ₹22.5 lakh invested, or about 3% of the corpus.
What is the PPF maturity formula? For a yearly deposit made at the start of the year, maturity is the future value of an annuity due: M = P x [((1 + i)^n - 1) / i] x (1 + i), where P is the annual deposit, i the annual rate, and n the years. Many published calculators print the ordinary-annuity version without the trailing (1 + i), which produces ₹37,98,515 on the standard example against the ₹40,68,209 they display.
How much can I invest in PPF per year? You can deposit a minimum of ₹500 and a maximum of ₹1,50,000 in a PPF account per financial year, in a lump sum or up to 12 installments. Deposits above ₹1.5 lakh earn no interest and no tax benefit, which is why this calculator caps the yearly amount at ₹1.5 lakh.
How is PPF taxed? PPF is fully exempt-exempt-exempt (EEE): the deposit earns a Section 80C deduction of up to ₹1.5 lakh, the interest is tax-free, and the maturity amount is tax-free. The 80C deduction is available only under the old tax regime, while the tax-free interest and maturity apply regardless of regime.
Can I withdraw from PPF before 15 years? Partial withdrawal is allowed from the 7th financial year, once a year, capped at 50% of the lower of the balance at the end of the 4th preceding year and the balance at the end of the previous year. The account stays open and keeps earning.
What is PPF premature closure and what does it cost? Premature closure shuts a PPF account after 5 complete financial years, and it is permitted only for serious illness, higher education, or a change of residency status. Interest is then recomputed 1% lower for every year the account ran, so this is the rule often misquoted as "withdrawal after 5 years".
Can I take a loan against my PPF? A loan is available from the 3rd to the 6th financial year, capped at 25% of the balance at the end of the second preceding financial year. It carries interest at the PPF rate plus 1%, must be repaid within 36 months, and anything outstanding after that is charged at the PPF rate plus 6%.
What happens to a PPF account after 15 years? You can withdraw the full balance tax-free, extend in 5-year blocks with fresh deposits by filing Form H within one year of maturity, or extend without deposits. Depositing into a matured account without filing Form H makes those amounts irregular, and they earn no interest.