How the math works
This calculator uses the future-value-of-annuity-due formula — the same one every bank’s PPF calculator uses:
FV = P × [((1+r)^n − 1) / r] × (1+r)Where:
- P = your yearly deposit
- r = annual interest rate (e.g. 0.071 for 7.1%)
- n = number of years
The (1+r) multiplier at the end accounts for the assumption that you deposit at the start of each financial year — so each year’s deposit earns one full year of interest before the next deposit goes in. Real PPF rules allow up to 12 instalments per year; this calculator assumes a single lump sum on April 1 for maximum compounding.
The year-by-year breakdown shows you the iterative version: start-of-year balance + deposit, then annual interest applied, repeated for the tenure.
Why PPF matters more than most realise
Three things converge in PPF that almost nothing else in the Indian retail market offers:
- Govt-backed safety. Sovereign risk only — practically zero default risk.
- EEE tax status. Deduction in, no annual tax, tax-free at withdrawal. Over 15 years at 7.1%, the implicit tax saving is enormous.
- Compounding without leakage. Most fixed-income products tax interest at slab rate annually — meaning a 30%-bracket investor loses ~30% of each year’s interest to tax, and the next year compounds on a smaller base. PPF compounds on the full interest because none of it is taxed.
The result: at the ₹1.5 lakh annual cap, a 15-year PPF returns roughly ₹40.7 lakh maturity — about ₹22.5 lakh of your money and ₹18.2 lakh of interest. The same ₹22.5 lakh deposited into a taxable FD at the same 7.1% would return roughly ₹35.5 lakh after 30%-bracket tax — a 12% gap that compounds with longer tenures.
Privacy
The math runs entirely in your browser via the pure calculatePPF function (src/tools/calculators/ppf-calculator.ts in our public repo). Editing any field produces zero network calls — you can verify this in your browser’s Network tab. The page doesn’t store inputs in localStorage, doesn’t include them in analytics, and never transmits anything about your investment plan.