Key takeaways
- PPF gives guaranteed, tax-free returns at a government-set rate, reviewed quarterly
- Interest is calculated monthly on the lowest balance between the 5th and last day of the month, but credited only once a year on 31 March
- Always deposit before the 5th of the month to earn interest for that month, rather than losing it
- The calculator's Tax Settings let you see your estimated 80C saving by tax slab — but this benefit only applies under the old tax regime
- Partial withdrawals are allowed from the 7th financial year onward — not immediately after 5 years, a common misconception
Understanding PPF interest calculation
PPF interest is calculated monthly but credited annually, on 31 March. The detail that trips people up: interest for a given month is calculated on the balance between the 5th and the last working day of that month — not on whatever your balance happens to be on the day you check it.
This means if you deposit on the 6th of a month, you miss that entire month's interest. If you deposit on or before the 5th, you earn interest for that month.
The single best practice for PPF: if you're depositing yearly, do it before 5 April each year — this earns you interest for April, the first month of the financial year, instead of losing it. Over 15 years, this timing difference alone can add a meaningful amount to your maturity value. The calculator surfaces this same reminder directly under the deposit field.
Try the PPF Calculator
Calculate your PPF maturity value, yearly interest breakdown, and 15-year schedule.
Yearly vs monthly deposits
The calculator lets you choose between yearly and monthly deposit frequency. Both are valid ways to fund the same annual ₹1,50,000 cap — the choice mostly comes down to cash flow.
- Yearly: one lump sum, ideally deposited before 5 April to capture the full year's interest from month one
- Monthly: smaller, more manageable instalments spread across the year — just remember each month's deposit needs to land by the 5th to count for that month's interest
Using the Tax Settings (80C estimate)
Open "Tax Settings" and choose your tax slab (New Regime, 10%, 20%, or 30%) to see an estimated tax saving from your PPF contribution under Section 80C.
Important: Section 80C deduction is only available under the old tax regime. If you select "New Regime," the calculator correctly shows no 80C tax saving — but your PPF interest and maturity amount remain fully tax-free either way, since that EEE status isn't tied to which regime you choose. Only the upfront 80C deduction on your contribution is regime-dependent, not the tax-free growth itself.
Reading the four result cards
Total Invested: your cumulative deposits over the full tenure, shown alongside your per-year deposit amount and total years.
Interest Earned: the total interest accrued over the tenure, plus an approximate CAGR figure for context.
Tax Saved (80C): your estimated tax saving based on the slab you selected in Tax Settings — this will show ₹0 if you've selected "New Regime," which is expected and correct, not a bug.
Lock-in Period: your selected tenure (15, 20, 25, or 30 years, depending on any extension blocks chosen) along with an estimated maturity date.
The lock-in timeline and its milestones
The Lock-in Milestones bar visually maps out four key stages of your account:
- Loan facility (years 3–6): you can borrow against your PPF balance — up to 25% of the balance at the end of the 2nd year preceding your application — without withdrawing principal or interrupting compounding
- Partial withdrawal (from year 7): you can withdraw up to 50% of the balance at the end of the 4th preceding year, or the immediately preceding year, whichever is lower — once per financial year
- Full maturity (15 years): withdraw the entire tax-free corpus, or choose to extend
- Extension (+5-year blocks): continue the account after maturity, with or without further contributions
Common misconception: partial withdrawal is often assumed to be available "after 5 years." The actual rule is the 7th financial year from account opening — which, since the 3rd–6th year loan facility and the 5-year premature-closure eligibility both involve similar-sounding timeframes, is an easy detail to mix up.
After 15 years: your three options
1. Withdraw fully: close the account and take the entire tax-free corpus, no penalty.
2. Extend without contribution: leave the balance in for another 5-year block, continuing to earn interest, with no further deposits required. You can withdraw any amount once per year during this period.
3. Extend with contribution: continue depositing up to ₹1,50,000/year for another 5-year block, keeping your 80C eligibility active (under the old regime). Withdrawals during this block are capped at 60% of the balance at the start of that block, taken as a lump sum or across the block.
The calculator's "Base + Extension Blocks" buttons let you model any of these — 15 years (base), or extended to 20, 25, or 30 years in 5-year increments — directly, without recalculating by hand.
Comparing two scenarios side by side
Open "Scenario Comparison" to test a change without losing your current numbers. Scenario A is pre-filled with your current values; Scenario B defaults to the same setup with 5 extra years of tenure, though every field is independently editable.
Common comparisons worth running here:
- 15-year vs 20-year tenure on the same yearly deposit — to see how much extending affects your final maturity value
- A smaller deposit for a longer period vs a larger deposit for the base 15 years — useful for deciding whether to max out your yearly contribution or extend the account instead
Click "Compare Scenarios" for a side-by-side table. If you edit an input after running a comparison, a notice reminds you to refresh the results.
Using the interest accrual schedule
Under "Interest Accrual Schedule," three views are available:
Chart view: a year-by-year line comparing total invested against your growing balance. Click any point for that year's deposit, interest accrued, and closing balance.
Yearly table: a row-by-row breakdown — deposit that year, cumulative invested, interest accrued, and closing balance — useful for seeing exactly how much of your later-year growth comes from interest rather than fresh deposits.
Monthly table: the full month-by-month figures. Worth remembering: monthly interest accrues but isn't actually credited to your account until 31 March each year, so the running balance shown here reflects pending accrued interest, not a monthly payout.
A few things worth keeping in mind
On the interest rate: PPF's rate is set by the government and reviewed quarterly. The calculator locks in the current rate automatically (shown with a "Govt. Locked" badge) so you don't need to enter it manually — but if you're projecting many years ahead, keep in mind the actual rate you'll earn in future years may differ from today's rate, since it's revised periodically rather than fixed for your full tenure.
These are estimates, not guarantees of your exact bank statement. Small differences can arise from exact deposit dates, how your specific bank or post office rounds figures, and the precise timing of the 5th-of-month interest cutoff. For your exact balance, always check your PPF passbook or net banking statement directly.
