Compound Interest Calculator
Calculate compound interest on any principal. Choose compounding frequency, rate and tenure to see the maturity amount and total interest earned.
Formula last reviewed 4 August 2026 · How we verify our calculators
Maturity amount
- Principal
- ₹1,00,000
- Total interest
- ₹61,051
Updates live as you type
Frequently asked questions
Compound interest is interest earned on both your original principal and the interest already accumulated. Over time this "interest on interest" causes growth to accelerate.
More frequent compounding (monthly vs annually) earns slightly more, because interest is added to the balance sooner and starts earning itself faster.
A = P × (1 + r/n)^(n×t), where P is principal, r is the annual rate, n is the compounding frequency and t is the time in years.
Simple interest is calculated only on the principal, so it grows linearly. Compound interest grows on an ever-larger base, so the gap widens dramatically over long periods.
₹1,00,000 at 10% doesn't earn ₹10,000 a year, every year
That's the assumption simple interest would make — a flat ₹10,000 annually, forever. Compound it instead over 5 years and the real number is ₹1,61,051, not ₹1,50,000, because from year two onward you're no longer earning interest on just the original ₹1,00,000 — you're earning it on the ₹1,00,000 plus every rupee of interest already credited. That extra ₹11,051 is "interest on interest," and it's the entire reason compound interest is worth understanding separately from simple interest.
A = P × (1 + r/n)ⁿᵗ is the formula behind it: P the principal, r the annual rate, n how many times a year interest compounds, t the time in years. Every time interest lands, it stops being "interest" and becomes part of next period's base — which is what bends the growth curve upward instead of leaving it a straight line. At the defaults above, annual compounding over 5 years turns ₹1,00,000 into that ₹1,61,051 maturity figure.
Compounding frequency moves the number less than people expect
Switch the same deposit from annual to quarterly compounding and the total does rise, because interest starts earning on itself four times a year instead of once — but the jump is small next to what a longer tenure does to the same principal. This surprises people who assume "monthly compounding" is some kind of hack; it's a real, measurable edge, just a modest one.
The lever that actually matters is time
Doubling your tenure from 5 to 10 years at an identical rate grows your final balance by more than switching from annual to monthly compounding ever could, because the curve gets steeper the longer it's allowed to run. That's the practical case for starting early with a fixed deposit, a recurring deposit or any interest-bearing instrument rather than waiting to invest a larger amount later — the years you wait cost more than the extra principal gains you back. Use this calculator to model FDs, bonds and any account where interest is reinvested rather than paid out to you, and to see, in real rupees, why patience is a bigger lever than the rate you're chasing.