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 July to September 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 Rs 1,50,000 a year for 15 years at 7.1% grows to about Rs 40.68 lakh, of which Rs 18.18 lakh is interest on Rs 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 is 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 rather than approximating a year of deposits as a single lump sum. The difference is real money. A single Rs 1.5 lakh deposit in April earns interest on the whole amount for all 12 months, but Rs 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 Rs 39.45 lakh against the yearly lump sum's Rs 40.68 lakh, a gap of roughly Rs 1.24 lakh on the same Rs 22.5 lakh invested. Miss the 5th on a monthly deposit and the loss grows: a two-day delay can forfeit a month's interest on that installment.
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) matters, because the April deposit earns interest that same year. Many published calculators print the formula without it, then quote a maturity figure that only the annuity-due version produces.
That closed form works for a clean yearly deposit. For monthly deposits it overstates the return, 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 Rs 1.5 lakh yearly deposit, the first year earns Rs 10,650 of interest, but by the final year the account is throwing off about Rs 2.7 lakh of interest annually, more than the Rs 1.5 lakh you put in.
| Year | Deposit | Interest that year | Balance |
|---|---|---|---|
| 1 | Rs 1,50,000 | Rs 10,650 | Rs 1,60,650 |
| 8 | Rs 1,50,000 | Rs 1,09,661 | Rs 16,54,185 |
| 15 | Rs 1,50,000 | Rs 2,69,695 | Rs 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 Rs 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 Rs 1.5 lakh saves Rs 46,800 in tax each year including the 4% cess, which is Rs 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 regardless. Set the calculator to the new regime and the tax-saved figure drops to zero.
Deposit limits, lock-in, withdrawal and loan
A PPF account takes between Rs 500 and Rs 1,50,000 per financial year, in a lump sum or up to 12 installments. Anything above Rs 1.5 lakh earns no interest and no deduction, so the calculator caps the yearly amount there. The account locks in for 15 years from the end of the financial year in which it was opened, and after that you can extend it in blocks of 5 years, with or without further deposits.
The lock-in is not absolute. Partial withdrawal is allowed from the 7th year, up to 50% of the balance at the end of the 4th preceding year, and a loan against the balance is available from year 3 to year 6, up to 25% of the balance. Both leave the account open and compounding.
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 Rs 1.25 lakh |
| 80C deduction | Up to Rs 1.5 lakh (old regime) | Up to Rs 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, not on a rule of thumb.
What this does not promise
The 7.1% rate is not fixed for the life of your account. The government resets PPF every quarter, so a 15-year projection at today's rate is a planning estimate, and the real maturity will drift as the rate changes. 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 July to September 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 Rs 1.5 lakh in April gives about Rs 40.68 lakh after 15 years at 7.1%, while Rs 12,500 a month gives about Rs 39.45 lakh, a difference of roughly Rs 1.24 lakh for the same Rs 22.5 lakh invested.
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. This calculator instead simulates the 12 monthly minimum balances directly, so monthly deposits are handled correctly.
How much can I invest in PPF per year? You can deposit a minimum of Rs 500 and a maximum of Rs 1,50,000 in a PPF account per financial year, in a lump sum or up to 12 installments. Deposits above Rs 1.5 lakh earn no interest and no tax benefit, which is why this calculator caps the yearly amount at Rs 1.5 lakh.
How is PPF taxed? PPF is fully exempt-exempt-exempt (EEE): the deposit earns a Section 80C deduction of up to Rs 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.
What is the PPF lock-in and can I extend it? PPF has a 15-year lock-in from the end of the financial year in which you opened it. After 15 years you can extend the account in blocks of 5 years, with or without further contributions, which is why this calculator lets you set the tenure to 20, 25, or more years.
Can I withdraw from PPF before 15 years? Partial withdrawal is allowed from the 7th year, up to 50% of the balance at the end of the 4th preceding year. A loan against the balance is available from year 3 to year 6, up to 25% of the balance. The account otherwise stays locked until maturity.