Compound Interest Calculator – Calculate Maturity Value

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Year-wise Breakdown

Compound Interest Calculator: Calculate How Your Money Grows

Last updated: 20 August 2026

Compound interest is what happens when the interest your money earns gets added back to the principal, so the next round of interest is calculated on a bigger base. Over enough years this snowball effect can turn a modest, regular investment into a corpus worth several times what you actually put in. This calculator works out that growth for you. Enter a lump sum, an optional top-up (monthly, quarterly, half-yearly or annual), the rate you expect to earn, and how often that rate compounds — you'll see the maturity value, the total interest earned, and a year-by-year breakdown of how the balance builds.

What is compound interest and how is it calculated?

Compound interest is interest calculated on the initial principal as well as on the interest that has already accumulated in earlier periods. That is the difference from simple interest, where you only ever earn a return on the original amount — with compounding, your earnings start earning too, and the gap between the two widens every year.

For a one-time lump sum, the maturity value is:

A = P × (1 + r / (100 × n))^{(n × t)}

P is the amount invested, r is the annual interest rate as a percentage, n is the number of times interest compounds each year (12 for monthly, 4 for quarterly, 2 for half-yearly, 1 for annual) and t is the tenure in years.

If you are also adding a regular top-up — this calculator supports monthly, quarterly, half-yearly or annual additions — each contribution is treated as its own deposit that compounds from the date it is paid until the end of your investment horizon, and all of those are added to the compounded lump sum. That is why a ₹1,00,000 lump sum with a ₹5,000 monthly top-up for 10 years, left to run for a 20-year horizon at 10% p.a. compounded quarterly, reaches ₹34,80,780 — well above what either the lump sum or the top-ups would earn on their own.

Current FD interest rates in India

This calculator is often used to work out what a bank fixed deposit will be worth at maturity, since most FDs pay compound interest at a fixed frequency — enter the FD's rate and compounding frequency in place of an assumed return. Rates differ by bank and tenure, and senior citizens usually get an extra 0.25 to 0.50 percentage points. Check the rate your own bank is offering before relying on the calculator's 10% default — the figures below are indicative and are reviewed periodically.

Rates as on 17 August 2026.

Source: BusinessToday — "8% FD interest is still available: These banks offer the highest rates in August 2026", 17 Aug 2026. Small finance bank deposits carry the same ₹5 lakh DICGC insurance cap per depositor per bank as larger banks, but sit in a different risk category.

Compound interest maturity value at a glance

The table below shows how a one-time lump sum grows at the calculator's default 10% p.a., compounded quarterly, with no additional top-up — a quick reference before a reader plugs in their own numbers.

A ₹1,00,000 lump sum left to compound for 20 years at 10% p.a. quarterly grows to ₹7,20,957 — more than seven times the original amount, without a single additional rupee invested.

How compounding frequency changes your effective return

The rate your bank or the calculator quotes is a nominal annual rate. Because interest is added to your balance more than once a year and then starts earning interest itself, what you actually earn over 12 months is slightly higher than that headline figure — the calculator reports this as the effective annualised yield.

At the default 10% p.a., the effective yield works out to 10.47% p.a. with monthly compounding, 10.38% with quarterly, 10.25% with half-yearly, and exactly 10.00% with annual compounding, since there is no intra-year compounding left to capture. The gap widens as the nominal rate rises, but at typical fixed-deposit rates it rarely exceeds half a percentage point.

Lump sum, SIP or both — what this calculator actually computes

This tool does more than a plain compound-interest formula: alongside a one-time lump sum, you can add a recurring monthly, quarterly, half-yearly or annual investment, and run that recurring contribution for a shorter period than the total investment horizon — so you can model, for example, ten years of monthly top-ups followed by another ten years of the balance compounding untouched.

If you are investing a lump sum only, this calculator gives the same answer as the formula above. If you are investing a fixed amount every month with no lump sum, the result lines up with our SIP Calculator instead, and if you want to see a lump sum and a step-up SIP broken out separately, our Lump-Sum Calculator and Top-up SIP Calculator handle each of those individually. Use whichever tool matches the shape of your actual cash flow.

Tax on interest earned from compounding investments

Interest earned on a fixed deposit, recurring deposit or any other compounding bank investment is fully taxable. It is added to your "Income from Other Sources" and taxed at your income-tax slab rate — there is no concessional rate and no Section 80C deduction on the deposit itself.

Banks deduct TDS at 10% under Section 194A once the total interest they pay you in a financial year crosses ₹50,000 — ₹1,00,000 if you are a senior citizen — across all your deposits with that bank taken together. If your total income for the year is below the taxable limit, submit Form 15G, or Form 15H if you are a senior citizen, to stop the deduction at source; if TDS has already been deducted and you owe less, claim it back when you file your return.

How to use this compound interest calculator

1. Enter the lump sum you are starting with, and — if you are also investing regularly — the amount of your monthly, quarterly, half-yearly or annual top-up.
2. Set the contribution frequency for that top-up, and separately the compounding frequency your bank or investment actually uses — most Indian bank FDs compound quarterly.
3. Set how long you will keep contributing and your total investment horizon (the two can differ, if you plan to stop contributing and let the balance keep compounding), then enter the annual interest rate you expect. The maturity value, total invested, interest earned and year-wise breakdown update instantly.