FORMULA

PPF Formula

The PPF maturity formula explained with variable definitions and a worked example — how yearly deposits compound annually into your final corpus.

Written by Anurag Rath · Reviewed by the thecalcu.com team · Last updated July 19, 2026

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The PPF (Public Provident Fund) maturity formula calculates how a series of fixed yearly deposits grows into a lump sum at maturity, with interest compounding annually. PPF is a government-backed, long-term savings scheme in India, and this formula uses the annuity-due convention since deposits are treated as made at the start of each financial year.

Formula

FV = P × [(1 + r)ⁿ − 1] / r × (1 + r)

Variable	Meaning
FV	Future value, your maturity amount
P	Fixed yearly deposit
r	Annual PPF interest rate (as a decimal, e.g. 7.1% = 0.071)
n	Number of years invested

Worked Example

Depositing the maximum ₹1,50,000 per year for 15 years at the current 7.1% annual rate:

Annuity growth factor: [(1.071)¹⁵ − 1] ÷ 0.071 × 1.071 = 27.1214
FV = 1,50,000 × 27.1214 = ₹40,68,209
Total invested: ₹1,50,000 × 15 = ₹22,50,000
Interest earned: ₹40,68,209 − ₹22,50,000 = ₹18,18,209

The interest earned (₹18.18 lakh) comes close to matching the total amount deposited (₹22.5 lakh), showing how much annual compounding adds over a full 15-year PPF term even though every deposit is capped at ₹1.5 lakh per year.

Key Things to Know

PPF compounds annually, not monthly or quarterly, so interest is calculated and credited to the account balance once a year, a slower compounding cadence than most bank fixed deposits.
The government sets the rate every quarter, so a real PPF account's growth is a chain of shorter compounding periods at slightly different rates rather than one constant rate for 15 years. This formula uses a single rate as a simplifying assumption for projection.
Depositing early in the financial year matters because PPF interest is calculated on the lowest balance between the 5th and last day of each month, a deposit made in April earns interest for the full year, while the same deposit made in March earns almost none for that year.
The 15-year minimum term is non-negotiable for the primary lock-in, though partial withdrawals are allowed from the 7th year onward, this formula only models the maturity value, not partial withdrawal scenarios.

Frequently Asked Questions

What does each variable in the PPF formula mean?

P is your fixed yearly deposit, r is the annual PPF interest rate (currently 7.1%, set by the Government of India every quarter), and n is the number of years you invest for, typically 15 at minimum. FV is the maturity amount your account holds at the end of the term.

Why does the formula multiply by (1+r) at the end?

PPF follows an annuity-due convention, meaning each year's deposit is treated as invested at the start of that year rather than the end. The extra (1+r) factor gives that deposit a full year of interest in its first year, matching how PPF actually credits interest annually.

Does the PPF interest rate stay fixed for the full 15 years?

No, the Government of India revises the PPF rate quarterly, so the actual rate applied to your balance can change several times over a 15-year account life. The formula here uses a single constant rate for simplicity, which is why it's a projection rather than a guarantee.

What happens after the PPF account reaches its 15-year maturity?

You can withdraw the full amount, or extend the account in blocks of 5 years, either continuing to deposit or leaving the balance to keep compounding without new contributions. Each extension effectively restarts the formula with a new n for that block.

Where can I calculate my own PPF maturity amount?

Use the [PPF Calculator](/in/ppf-calculator/) to enter your yearly deposit, the current interest rate, and your investment period rather than computing the formula by hand, it applies the exact same maths shown here instantly.