See how a lump sum (or a lump sum plus regular top-ups) grows with compound interest — compare compounding frequencies, check the Rule of 72, and view a year-wise growth schedule.
| Year | Opening Balance | Interest Earned | Closing Balance |
|---|
| Compounding | Maturity Value | Interest Earned |
|---|
Key Takeaways
- Compound interest earns interest on interest, unlike simple interest, which is always calculated on the original principal alone — the gap between the two widens every year.
- More frequent compounding gives a slightly higher return at the same stated annual rate, because interest starts earning its own interest sooner. The jump from annual to daily compounding on a typical FD rate is usually a modest but real difference, not a dramatic one.
- The Rule of 72 is a fast mental-math shortcut, not an exact formula: dividing 72 by the annual interest rate gives a rough number of years for a lump sum to double, which gets less accurate at very high or very low rates.
What This Compound Interest Calculator Does
This calculator projects how a fixed deposit, recurring deposit, or any interest-bearing investment grows over time using compound interest — the mechanism where each period's interest is added back to the principal so future interest is earned on a larger base. It supports every common compounding frequency (annually, semi-annually, quarterly, monthly, or daily), lets you optionally add a regular top-up contribution on top of the initial lump sum, and includes a live Compare Compounding Frequencies table so you can see exactly how much difference the compounding schedule itself makes to the same deposit. A Rule of 72 estimate and a full year-wise growth schedule round it out.
Everything runs entirely in your browser. No amount, rate, or tenure you enter is sent to a server, logged, or stored anywhere — close the tab and it's gone. There's no signup, no email wall, and no ads inside the calculator itself. Whether you're comparing a bank's fixed deposit quote, projecting a recurring deposit, or just curious how compounding actually works, adjust any field and every result updates instantly.
How to Use This Compound Interest Calculator
The calculator has one main flow with an optional add-on. Here's exactly how to use each part, with a worked example for each.
1. Basic Lump-Sum Growth
- Enter your Principal Amount.
- Enter the Annual Interest Rate.
- Enter the Time Period in years.
- Choose a Compounding Frequency.
2. Add a Regular Top-Up
- Tick Add a regular top-up contribution.
- Enter the amount added every compounding period (so "per Quarter" if Quarterly is selected).
- The Maturity Value now includes both the lump sum's growth and the top-ups' own growth.
3. Compare Compounding Frequencies
- Set up your Principal, Rate, and Years as usual.
- Click Compare Compounding Frequencies.
- See the same deposit's maturity value under all five frequencies side by side.
4. Year-wise Growth Schedule
- Click View Year-wise Growth Schedule.
- See each year's opening balance, interest earned that year, and closing balance.
- Use Download as .txt to save your current result and stats.
The Compound Interest Formula, Explained
The standard compound interest formula for a lump sum is:
A = P × (1 + r/n)n × t
Where A is the maturity value, P is the principal, r is the annual interest rate (as a decimal), n is the number of times interest compounds per year, and t is the time in years. When a regular contribution C is added every compounding period, its own future value is added on top using the standard annuity formula: C × [((1 + r/n)nt − 1) / (r/n)].
Worked example: Principal P = INR 1,00,000, annual rate r = 8%, time t = 5 years, compounded quarterly (n = 4).
- Periodic rate: r/n = 0.08 / 4 = 0.02
- Number of periods: n × t = 4 × 5 = 20
- (1.02)20 ≈ 1.48595
- A = 1,00,000 × 1.48595 ≈ INR 1,48,595
Interest earned works out to about INR 48,595 on an INR 1,00,000 deposit — compare that to simple interest at the same 8% rate over 5 years, which would earn only INR 40,000, because simple interest never compounds on itself.
Compounding Frequency & Simple vs Compound Interest: Reference Table
The table below shows how much the compounding schedule alone changes the outcome for the same INR 1,00,000 deposit at 8% p.a. for 5 years, plus a simple-interest baseline for comparison.
| Method | Maturity Value | Interest Earned |
|---|---|---|
| Simple Interest | INR 1,40,000 | INR 40,000 |
| Compound – Annually | INR 1,46,933 | INR 46,933 |
| Compound – Semi-Annually | INR 1,48,024 | INR 48,024 |
| Compound – Quarterly | INR 1,48,595 | INR 48,595 |
| Compound – Monthly | INR 1,48,985 | INR 48,985 |
| Compound – Daily | INR 1,49,176 | INR 49,176 |
Quick Definitions
Compound interest is interest calculated on both the original principal and the interest already accumulated in previous periods, so the amount earning interest grows over time. Simple interest, by contrast, is always calculated on the original principal alone, so it grows in a straight line rather than accelerating.
Frequently Asked Questions
Each compounding period adds that period's interest back into the balance, so the next period's interest is calculated on a slightly larger amount. The more often this happens, the sooner interest starts earning its own interest, though the effect shrinks as frequency increases — the jump from monthly to daily is much smaller than from annual to quarterly.
A SIP always assumes equal contributions at fixed intervals with no separate lump sum. This calculator handles a pure lump sum, a pure recurring contribution, or both together, and lets you choose the compounding frequency explicitly rather than assuming monthly.
It's a quick mental shortcut: divide 72 by the annual interest rate to estimate how many years it takes a lump sum to double. At 8%, that's 72 / 8 = 9 years — close to, but not exactly, the precise compound-interest answer.
Yes, interest earned on fixed and recurring deposits is added to your taxable income under current Indian tax rules, and banks deduct TDS above a threshold. This calculator shows the pre-tax maturity value; consult a tax professional or the current Income Tax Department rules for your specific liability.
Less than you'd expect. Over a 1-year deposit, the gap between annual and daily compounding at a typical FD rate is usually a small fraction of a percent of the total; the difference becomes more noticeable only over longer tenures.
No. Every calculation runs locally in your browser using JavaScript; nothing you type is transmitted to any server, logged, or saved once you close or refresh the page.