What is Compound Interest?
Compound interest is the interest calculated on the initial principal and also on the accumulated interest of previous periods of a deposit or loan. It is often called “interest on interest” and makes a sum grow faster than simple interest.
The Compound Interest Formula
The formula for compound interest is:
A = P (1 + r/n)^(nt)
- A = Final amount
- P = Principal (initial investment)
- r = Annual interest rate (decimal)
- n = Number of times interest compounds per year
- t = Time in years
Example Calculation
Suppose you invest ₹1,00,000 at 8% annual interest, compounded monthly for 5 years:
- P = 1,00,000
- r = 0.08
- n = 12
- t = 5
A = 1,00,000 × (1 + 0.08/12)^(12×5) = ₹1,48,977
Your investment grows by ₹48,977 — purely from compounding!
Daily vs Monthly vs Annual Compounding
The frequency of compounding matters. The more often interest is compounded, the faster your money grows:
- Daily compounding — 365 times per year
- Monthly compounding — 12 times per year (most common)
- Quarterly compounding — 4 times per year
- Annual compounding — once per year
Power of Compound Interest Over Time
Albert Einstein reportedly called compound interest the “eighth wonder of the world.” The key is time — the longer your money compounds, the more dramatic the growth becomes.
Starting to invest early, even with small amounts, can lead to significantly greater wealth compared to starting late with larger amounts.
Use Our Free Compound Interest Calculator
You can use our free compound interest calculator to instantly calculate returns for any principal, interest rate, and time period. No signup required!
Tips for Maximizing Compound Returns
- Start investing as early as possible
- Reinvest all earnings and dividends
- Choose accounts with higher compounding frequency
- Avoid withdrawing principal during the compounding period
- Stay invested through market fluctuations for long-term gains
