What is the Compound Interest Calculator?
Compound interest is often called the eighth wonder of the world because it makes money grow on money already grown. The FinanceDeck Compound Interest Calculator lets you see, in real time, how a lump sum grows over any tenure with monthly, quarterly, half-yearly or yearly compounding.
Every long-term savings product — from FDs and PPF to mutual funds and stocks — relies on compounding to build wealth. Modelling it explicitly with your own numbers is the fastest way to internalise why starting early matters more than starting big.
How does it work?
The calculator uses the classic compound interest formula A = P(1 + r/n)^(n×t) where P is principal, r is annual rate, n is compounding frequency per year and t is time in years. Change any input and result updates instantly.
The compounding frequency has a smaller effect than most people expect — the gap between yearly and monthly compounding on the same 10% rate over 10 years is only about 2%. The tenure and rate matter far more.
A = P × (1 + r/n)^(n × t)Example
Invest ₹1,00,000 at 10% for 10 years, compounded quarterly.
The maturity value is ₹2,68,506 — you more than double your money without adding a single rupee. Extend the tenure to 20 years and it grows to ₹7,20,957. That's the eighth wonder in action.
Benefits
- ✓Understand the eighth wonder of the world
- ✓Compare monthly vs. yearly compounding
- ✓Model long-term goals like retirement corpus
- ✓See exactly what starting 5 years earlier does
- ✓No login, no data stored, works offline
Frequently Asked Questions
Which compounding frequency should I use?
Match it to the product — FDs are typically quarterly, PPF yearly, mutual funds effectively daily. When in doubt, quarterly is a fair default for Indian bank products.
Compound vs. simple interest — which is bigger?
Compound always wins over long tenures. Over 20 years at 10%, compound doubles the outcome of simple interest.
Does it account for tax?
No. This is a pre-tax calculation. Post-tax returns are typically 1–2% lower for high tax brackets.
Is inflation included?
No. Use the Inflation Calculator to convert future value back to today's rupees.
Related Calculators
Plan every goal in one place
Combine your loans, SIPs and savings inside the free FinanceDeck Planner.
Learn more in the Learning Center
Deep-dive guides that explain the concepts behind the Compound Interest Calculator.