PPF calculator

PPF rules the calculator follows

• Deposits: at least ₹500 and at most ₹1,50,000 in a financial year, in one lump sum or in instalments, and every deposit in multiples of ₹50 (Source: National Savings Institute, Ministry of Finance (Department of Economic Affairs), checked 26 October 2026). Amounts above ₹1,50,000 in a year earn no interest (Source: State Bank of India, checked 26 October 2026).
• Interest: earned each month on the lowest balance between the close of the 5th and the end of the month, and credited to the account at the end of each financial year (Source: National Savings Institute, Ministry of Finance (Department of Economic Affairs), checked 26 October 2026). That is why a deposit made by the 5th earns interest for that month, and why interest compounds once a year.
• Term: the account matures fifteen years after the end of the financial year in which it was opened (Source: National Savings Institute, Ministry of Finance (Department of Economic Affairs), checked 26 October 2026). So it runs for the opening year plus 15 more and can take a deposit in each of up to 16 financial years. After maturity it can be extended with deposits in blocks of 5 years, by applying within one year of maturity, or kept open without deposits while it continues to earn interest (Source: National Savings Institute, Ministry of Finance (Department of Economic Affairs), checked 26 October 2026).
• Rate: set by the government and notified each quarter by the Ministry of Finance (Source: Department of Economic Affairs (Budget Division), Ministry of Finance, checked 26 October 2026).
• Loans and withdrawals (not modelled here): a loan is possible after one year but before five years from the end of the year of the first deposit, up to 25% of the balance at the end of the second year before the loan year, and one withdrawal a year is allowed once five years have passed from the end of the opening year, within the scheme's limits (Source: National Savings Institute, Ministry of Finance (Department of Economic Affairs), checked 26 October 2026).
• Missed years (not modelled here): if a financial year after the opening year passes without the ₹500 minimum, the account is treated as discontinued, and loans and partial withdrawals are not allowed in it. Its balance continues to earn interest at the scheme rate, and it can be revived before maturity by paying ₹500 for each year missed plus a default fee (Source: National Savings Institute, Ministry of Finance (Department of Economic Affairs), checked 26 October 2026).

By default the calculator runs to maturity: the opening year plus 15 full financial years, with a deposit in each of the 16 years. Many calculators show only 15 deposits; choose "15 years only" to compare with them, but note that this stops one year before the account matures. The projection assumes you open the account and make each year's deposit by 5 April (or each monthly instalment by the 5th). If you open it later in the opening year, that year earns interest for fewer months, so the first year shown here is an upper estimate.

The calculation

For each financial year, with B_m the balance in month m after any deposit made by the 5th and R the yearly rate as a decimal:

The year's interest is added to the balance at 31 March and earns interest from the next year. With one deposit by 5 April, every month has the same balance, so the year's interest is simply (opening balance + deposit) × R, and n equal yearly deposits D grow to D × [(1 + R)ⁿ − 1] ÷ R × (1 + R), with n = 16 to maturity or 15 for the common illustration.