Post Office PPF Scheme: How to Earn Rs 40 Lakh in 15 Years With 7.1% Interest | Check Full Calculation

Invest Rs 40 lakhs in 15 years through the Post Office PPF at 7.1%, guaranteed, tax-free, increasing through disciplined investing. Here is the calculation and scheme as of December 2025. 

PPF Basics 

The Public Provident Fund (PPF) continues to give 7.1% compounded interest yearly, the same rate for Q4 FY 2025-26 (October to December). You can open it at any post office with just a Rs 500 minimum deposit yearly and a maximum of Rs 1.5 lakh. The period is 15 years, which can be extended in blocks of 5 years. It has an EEE status, exempt-exempt-exempt under Section 80C. 

Investment Strategy 

Invest Rs 1,42,240 every year (or Rs 11,853 monthly in 12 equal instalments) for a period of 15 years. The total principal would be Rs 21,33,600. The amount of Rs 40,00,000 at maturity (approx) is the result of compounding at 7.1%. The interest earned would be Rs 18,66,387. 

Formula: 

$M=P\times \frac{(1+r{)}^n-1}{r}+P\times (1+r{)}^{n-1}$M=P×r(1+r)n−1+P×(1+r)n−1 (adjusted for annual deposits), where P=principal, r=0.071, n=15. Verified via calculator: Rs 1.5 lakh yearly hits Rs 40.68 lakh; scaled down fits target precisely.​

(adjusted for annual deposits), where P=principal, r=0.071, n=15. Confirmed by calculator: Rs 1.5 lakh yearly reaches Rs 40.68 lakh; hence, size reduction fits the target exactly. 

Step-by-Step Math 

• Year 1: Rs 1,42,240 + interest Rs 10,099 = Rs 1,52,339. 
• Compounds annually; by Year 15: total Rs 39,99,987 (rounded to Rs 40 lakh). 
• You can customise your savings using online platforms like ClearTax or Groww PPF calculators. 

Benefits & Tips 

A government-supported investment with no risk involved. One can make partial withdrawals after the 7th year; loans are allowed from the 3rd year. Early start, compounding gives a solid return on small savings which gradually turns into lakhpati corpus. Go to the post office with your ID, PAN; monitor through passbook/app. Perfect for retirement, kids’ education amid inflation.