Compound Interest Calculator
See how a one-time amount — plus any monthly top-ups — snowballs as interest earns interest.
Plan your investment
8.30% effective yield at monthly compounding
Compounded 12× a year
Optional — leave at 0 for a pure lump sum
Results update live — calculations run in your browser, no signup.
₹2.22 L
In 10 yrs at 8.0% compounded monthly — 2.22× what you put in
Assumes a constant 8.0% nominal rate compounded monthly (12×/yr). A projection before tax and inflation — returns are not guaranteed.
How much of your ₹2.22 L future value is your own money versus pure compound interest.
Total invested
₹1.00 L
your own money · 45%
Interest earned
₹1.22 L
pure compounding · 55%
Opening balance, money added, interest credited and closing balance for each of the 10 years.
| Year | Opening | Added | Interest | Closing |
|---|---|---|---|---|
| Year 1 | ₹1.00 L | ₹1.00 L | ₹8,300 | ₹1.08 L |
| Year 2 | ₹1.08 L | — | ₹8,989 | ₹1.17 L |
| Year 3 | ₹1.17 L | — | ₹9,735 | ₹1.27 L |
| Year 4 | ₹1.27 L | — | ₹10,543 | ₹1.38 L |
| Year 5 | ₹1.38 L | — | ₹11,418 | ₹1.49 L |
| Year 6 | ₹1.49 L | — | ₹12,366 | ₹1.61 L |
What your ₹2.22 L will actually buy, in today's money, after 6% inflation. Toggle it into the main result:
Adjust the inflation rate under Advanced options in the inputs panel.
Does compounding frequency matter?
Same 8.0% nominal rate on ₹1,00,000 over 10 yrs — only how often it compounds changes. More frequent = a higher effective yield, but the gain is small.
| Compounding | Effective yield | Future value | vs annual |
|---|---|---|---|
| Annually (1×/yr) | 8.00% | ₹2.16 L | — |
| Half-yearly (2×/yr) | 8.16% | ₹2.19 L | +₹3,220 |
| Quarterly (4×/yr) | 8.24% | ₹2.21 L | +₹4,911 |
| Monthly (12×/yr) | 8.30% | ₹2.22 L | +₹6,072 |
Going from annual to monthly compounding lifts the effective yield from 8.00% to 8.30% — the rate and the time horizon do the heavy lifting, not the frequency.
Simple vs compound — the compounding advantage
Same 8.0% rate over 10 yrs. Simple interest only ever pays on your deposits; compound interest pays on the growing balance too.
Simple interest
₹1.80 L
interest never compounds
Compound interest
₹2.22 L
interest earns interest
Compounding earns you an extra ₹41,964 over simple interest — purely from interest-on-interest.
- 55% of the final value is interest — money you never deposited.
- Your balance doubles roughly every 8y 8m.
- After 6% inflation, it buys what ₹1.24 L buys today.
Rule of 72 — when your money doubles
A quick mental shortcut: 72 ÷ your rate ≈ years to double. Here's how it lines up with the precise figure.
Money doubles every
8y 8m
Rule of 72 estimate: 9.0 yrs · exact: 8.7 yrs
2×
₹2.00 L
in 8y 8m
4×
₹4.00 L
in 17y 5m
8×
₹8.00 L
in 26y 1m
What this means
Investing ₹1,00,000 for 10 yrs at 8.0% compounded monthly grows your ₹1.00 L into ₹2.22 L. Of that, ₹1.22 L is pure interest — a 2.22× return, with your balance doubling roughly every 8y 8m.
Key takeaways
- Total invested: ₹1.00 L
- Interest earned: ₹1.22 L
- Growth multiple: 2.22×
- Effective annual rate on your money: 8.30%
- Future value in 10 yrs: ₹2.22 L
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Your plan: ₹1,00,000 at 8.0% for 10 years → about ₹2.22 L.
Put compounding to work everywhere
Carry this growth engine into deposits and investments — FDs, RDs, future value and SIPs.
The figures above are a transparent projection from the inputs you choose — before tax and inflation — not a promise. Reference rates shown for context are typical long-term or illustrative figures, and actual returns vary year to year. Treat the result as a planning guide.
How compound interest is calculated
FV = P × (1 + r ÷ n)^(n × t)
- FV
- future value (maturity)
- P
- principal (one-time amount)
- r
- annual rate as a decimal = rate ÷ 100
- n
- compounding periods per year
- t
- number of years
Worked example
With your inputs — ₹1,00,000 at 8.0% compounded monthly (12×/yr) for 10 years: each period adds r ÷ n = 0.6667% over n × t = 120 periods, for an effective annual yield of 8.30%. That grows the principal to about ₹2.22L — roughly ₹1.22L of compound interest, a 2.22× return. It is a projection from your inputs, before tax and inflation, not a guaranteed return.
Most asked compound interest questions
Compound interest is interest earned on both your original principal and the interest already added to it. Because each period's interest is folded back into the balance, the growth accelerates over time — your interest starts earning interest, which is what turns a modest sum into a much larger one over the years.
Future value = P × (1 + r/n)^(n·t), where P is the principal, r is the nominal annual rate, n is the number of compounding periods per year, and t is the number of years. The interest earned is simply the future value minus everything you put in. With a monthly contribution, each deposit is also compounded from the day it goes in.
Yes, but less than most people expect for the same nominal rate. Compounding monthly instead of annually raises your effective yield only slightly. The bigger drivers of your final value are the rate itself and how long you stay invested — time does far more work than frequency.
The Rule of 72 is the quick shortcut: divide 72 by your annual rate to estimate the doubling time. At 8% that's about 9 years; at 12% about 6 years. This page shows both the Rule-of-72 estimate and the precise figure from your effective annual rate.
Simple interest is calculated only on your original principal, so the balance grows in a straight line. Compound interest is calculated on the principal plus all accumulated interest, so it curves upward and pulls away from simple interest more and more as the years pass. That widening gap is the whole point of compounding.
No. This is a transparent projection from the inputs you choose, not a promise. The reference rates shown for context (FD, PPF, equity, inflation) are typical long-term or illustrative figures, not guarantees, and actual returns vary year to year. Treat the result as a planning guide.
The complete guide to compound interest
Why compounding snowballs
Compound interest is interest that earns interest. Each period, the rate is applied to your principal plus all the interest accumulated so far, so the balance grows by a larger amount every step. Over long horizons this snowball effect is what turns a modest deposit into a much larger sum — and why doubling your horizon usually far more than doubles your money.
How the future value is calculated
This calculator compounds a one-time amount at a constant rate: FV = P × (1 + r/n)^(n·t), where n is the number of compounding periods a year. Any monthly contribution is added as a recurring deposit that compounds from the day it goes in. The doubling time comes from the effective annual yield, which the Rule of 72 (72 ÷ rate) closely approximates.
Does compounding frequency matter?
For the same nominal rate, more frequent compounding lifts the effective yield only slightly. Monthly compounding beats annual by a small margin — as the table above shows — because each extra fold-in earns interest a little sooner. The rate you earn and the time you stay invested matter far more than whether interest posts monthly or yearly.
Simple vs compound interest
Simple interest is charged only on the original principal, so the balance grows in a straight line. Compound interest is charged on the principal plus accumulated interest, so it curves upward and pulls away from simple interest more and more as the years pass. Most deposits, bonds and investments compound; many short-term loans use simple interest.
Treat the result as a projection
The figures here are a transparent projection from the inputs you choose, not a guaranteed return. Any reference rates shown for context are typical long-term or illustrative figures and vary year to year. Give your money time, keep the rate realistic, and treat this as a planning guide rather than a promise.
Adding to it every month
A small monthly contribution can dwarf the original lump sum over a long horizon, because every deposit gets its own runway to compound. Turning on the monthly contribution shows both your growing invested amount and the future value side by side, so you can see how regular investing and compounding reinforce each other.