Compound Interest Calculator Online – Calculate Maturity Amount & Interest Instantly
By LegalDev India Tax Team
Compound interest is calculated using A = P(1 + r/n)^(nt), where interest earned in each period gets added to the principal and itself starts earning interest in the next period. A ₹1,00,000 deposit at 10% for 5 years grows to ₹1,61,051 with annual compounding, versus ₹1,50,000 under simple interest — enter your own numbers below for an instant maturity figure.
Free Compound Interest Calculator
Enter your principal, annual rate, time period, and compounding frequency above to get your maturity amount and total interest earned instantly — free, no login, and it works the same on a phone as it does on a laptop. Calculate Compound Interest to see the result, Reset to start over, or Copy Result to paste it somewhere else.
Most bank FDs, recurring deposits, and the PPF account all compound interest rather than paying it flat, which is exactly why the maturity value on your passbook rarely matches a quick mental estimate of "rate times years." This calculator handles annual, half-yearly, quarterly, monthly, and daily compounding, and shows you the one number that actually lets you compare two differently-structured products fairly: the effective annual rate.
How to Use This Compound Interest Calculator
Enter the principal amount you're depositing or investing, the annual interest rate quoted to you, and the time period in years. Then pick the compounding frequency that matches your actual product — quarterly for most bank fixed deposits, annually for PPF, NSC, and most small savings schemes — since picking the wrong frequency is the single most common reason people's manual estimate disagrees with their bank statement.
The calculator returns the maturity amount, the total compound interest earned, and the effective annual rate, so you can see both what you'll end up with and what rate that actually works out to once compounding is factored in.
What You Can Calculate
Maturity Amount
The total value of your principal plus all compounded interest at the end of the term — what actually lands in your account or gets paid out on a loan, after every compounding period has done its work.
Interest Earned
The maturity amount minus your original principal, isolating exactly how much the compounding itself contributed versus what you put in.
Daily, Monthly, Quarterly or Annual Compounding
Switching the frequency on the same principal and the same quoted rate changes your result, because more frequent compounding means interest starts earning interest sooner. On ₹1,00,000 at 8% for one year: annual compounding yields exactly 8% (₹8,000 interest), while quarterly compounding yields an effective rate closer to 8.24% — a gap that widens, in rupee terms, the longer the money stays invested.
Key Features of Our Compound Interest Calculator
Covers all five standard compounding frequencies — daily, monthly, quarterly, half-yearly, and annual — not just the one your bank happens to default to
Shows the effective annual rate alongside the maturity amount, so you can compare a 7.5% annually-compounded FD against a 7.3% quarterly-compounded one without doing the algebra yourself
Free to use, with no login or signup required
Works on mobile as cleanly as on desktop
Instant results with no page reload
Compound Interest Calculation Example
You deposit ₹2,00,000 in a fixed deposit at 7.5% per annum, compounded quarterly, for 3 years. Using A = P(1 + r/n)^(nt): A = 2,00,000 × (1 + 0.075/4)^(4×3) = 2,00,000 × (1.01875)^12 ≈ ₹2,49,943. Compound interest earned = ₹49,943, against ₹45,000 you'd have earned on the same deposit under flat simple interest over the same 3 years — the gap exists purely because of quarterly compounding, not a different rate.
Worth flagging separately: this exact formula does not apply to a recurring deposit, even though an RD also compounds. An RD involves a fresh monthly contribution rather than one lump sum, so its maturity value follows a future-value-of-annuity calculation, not the single-lump-sum formula above — treating an RD like a one-time compound deposit will noticeably understate what it actually pays out.
Compound Interest vs Simple Interest
The difference is the base on which interest is calculated.
| | Simple Interest | Compound Interest |
|---|
| Calculation base | Always the original principal | Principal plus all interest already added |
| Growth pattern | Linear — the same rupee interest every period | Exponential — interest itself starts earning interest |
| Typical use in India | Gold loans, FDs under 6 months, informal lending | Bank FDs of 6 months and above (usually quarterly), PPF, NSC, SSY (annually), recurring deposits |
On a one-year, single-compounding-period deposit the two methods give an identical answer; the difference only shows up once the term runs past a single compounding cycle, and it keeps widening the longer the money sits.
Why Use LegalDev India's Compound Interest Calculator?
It handles every standard compounding frequency rather than assuming you want annual or quarterly by default, and it surfaces the effective annual rate so two products quoted differently — "7.5% compounded annually" versus "7.3% compounded quarterly" — can actually be compared on equal terms rather than left to a gut-feel guess. It's built for someone deciding between FD options or sanity-checking a bank's maturity projection, not for a classroom exercise in interest theory.
FAQs
A = P × (1 + r/n)^(n×t), where P is principal, r is the annual rate as a decimal, n is the number of compounding periods per year, and t is time in years. Compound interest earned equals A minus P.
Most scheduled commercial banks in India — SBI, HDFC, ICICI, and Axis among them — compound fixed deposit interest quarterly by default; a smaller number offer monthly compounding as an option, which produces a marginally higher effective yield at the same nominal rate.
Annually — interest on a Public Provident Fund account is calculated monthly on the lowest balance between the 5th and the end of each month, but credited to the account only once, on 31 March each year.
The nominal rate is the headline annual percentage a bank quotes; the effective annual rate (EAR) factors in how often that rate actually compounds, using EAR = (1 + r/n)^n − 1. A 12% nominal rate compounded monthly works out to roughly a 12.68% effective annual rate — the number that actually matters when comparing two products.
Not directly. An RD involves a new monthly deposit rather than a single principal, so its maturity value needs the future-value-of-annuity formula, not the single-lump-sum compound interest formula on this page.
Because interest gets added to the principal four times a year instead of once, so each quarter's interest starts earning its own interest sooner — the effect compounds over the compounding, which is the entire point of the calculation.
Yes, if you're the one earning it — more frequent compounding at the same nominal rate always produces a higher effective return. It cuts the other way on a loan: more frequent compounding on money you owe means you pay more in total, not less.
It grows with time. Over one year the gap between annual and quarterly compounding at a typical FD rate is usually under half a percentage point in effective terms, but over 10 or 20 years that gap compounds into a meaningfully larger rupee difference, which is why long-term investors pay closer attention to compounding frequency than short-term depositors do.
Yes — the National Savings Certificate and Kisan Vikas Patra both use annual compounding, consistent with most government small-savings instruments, which is why their n value in the formula is 1 rather than 4 or 12.