Compound Interest Calculator
See how an initial amount plus regular contributions can grow with compound interest — across any rate, duration, and compounding frequency.
Final Estimated Value
₹12,94,929
Monthly compounding at 10% p.a.
Total contributions
₹7,00,000
Estimated interest
₹5,94,929
- Total Contributions
- Est. Interest
Pin this scenario, change the inputs, and compare side by side.
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Growth over time
- Contributions
- Value
Scenario comparison
Same inputs, different assumed annual rates — an illustration, not a prediction.
6% p.a.
₹10,01,336
8% p.a.
₹11,36,694
10% p.a.
₹12,94,929
12% p.a.
₹14,80,232
Year-by-year table
| Year | Contributions | Est. Interest | Value |
|---|---|---|---|
| 1 | ₹1,60,000 | ₹13,299 | ₹1,73,299 |
| 2 | ₹2,20,000 | ₹34,274 | ₹2,54,274 |
| 3 | ₹2,80,000 | ₹63,727 | ₹3,43,727 |
| 4 | ₹3,40,000 | ₹1,02,548 | ₹4,42,548 |
| 5 | ₹4,00,000 | ₹1,51,716 | ₹5,51,716 |
| 6 | ₹4,60,000 | ₹2,12,316 | ₹6,72,316 |
| 7 | ₹5,20,000 | ₹2,85,544 | ₹8,05,544 |
| 8 | ₹5,80,000 | ₹3,72,723 | ₹9,52,723 |
| 9 | ₹6,40,000 | ₹4,75,313 | ₹11,15,313 |
| 10 | ₹7,00,000 | ₹5,94,929 | ₹12,94,929 |
Worked example
Starting with ₹1,00,000 and adding ₹5,000 every month for 10 years at 10% grows to about ₹12,94,929. You contribute ₹7,00,000 in total; the rest — ₹5,94,929 — is compounding at work.
Compound interest formula
With a lump sum only, the value grows as:
A = P × (1 + r/n)n×t
When you add regular contributions, each contribution also compounds for the remaining periods, which this calculator computes period by period.
Why time is the biggest lever
Because interest earns interest, the final years contribute the most growth. Extending the duration usually increases the outcome far more than a similar increase in contribution — try it with the sliders.
Simple vs compound interest
Under simple interest the balance rises by the same amount every year; under compound interest each year's interest is added to the base, so the yearly gain itself keeps growing. Over short periods the two are close; over decades they diverge sharply — the worked example below quantifies it. The Simple Interest calculator shows the straight-line case for the same inputs.
Worked example: ₹1,00,000 at 8%
Take ₹1,00,000 at an assumed 8% a year, compounded annually, with no further contributions.
- Year 1:
1,00,000 × 1.08 = ₹1,08,000(interest ₹8,000) - Year 2:
1,08,000 × 1.08 = ₹1,16,640(interest ₹8,640) - Year 3:
1,16,640 × 1.08 = ₹1,25,971(interest ₹9,331)
Interest grows each year because it is earned on a larger balance. Under simple interest the same deposit would earn a flat ₹8,000 every year — ₹1,24,000 after 3 years versus ₹1,25,971. Over 3 years the gap is small; over 20 years at the same rate it becomes ₹2,60,000 versus about ₹4,66,000.
With monthly compounding at the same 8% nominal rate, the effective annual rate is (1 + 0.08/12)12 − 1 ≈ 8.30%, so the year-1 balance would be about ₹1,08,300 instead of ₹1,08,000.
Rule of 72: a quick sanity check
Dividing 72 by the annual rate gives a rough number of years for money to double. At 8% that is about 9 years; at 6% about 12 years; at 12% about 6 years. It is an approximation — the calculator gives exact figures — but it is a handy way to check whether a result looks plausible.
Limitations
The calculator assumes one constant rate for the whole period, which real products rarely deliver: bank deposit rates are reset when you renew, and market-linked investments vary year to year. It also ignores tax on interest (see how FD/RD interest is taxed) and any fees, both of which reduce the effective rate. Use it to understand the mechanics and compare scenarios, not to forecast a specific outcome.
Assumptions & what this calculator does not include
- •Assumes a constant rate and regular contributions every period.
- •Contributions are added at the end of each compounding period.
- •Taxes and fees are not modelled.
- •Outputs are illustrations of your assumptions, not guarantees.
Frequently asked questions
Methodology last reviewed: 16 October 2026
How we maintain this page: the formula is covered by automated tests, default rates that depend on government notification are re-checked when a revision is announced, and the content and links are re-read when a reader reports an issue or the page is edited. See our Calculator Methodology and Corrections Policy.