The rate you enter, 2%, is the nominal annual rate. Because it compounds 1 time(s) a year, the effective annual rate — what you actually earn over a full year after reinvesting each period's interest — works out to about 2.00%, using EAR = (1 + R/(100n))ⁿ − 1. The more frequently interest compounds within the year, the larger this gap between nominal and effective rate becomes, even though the nominal rate never changes.

This distinction matters when comparing two deposit or loan products that quote the same nominal rate but compound at different frequencies — the one that compounds more often (say, monthly versus annually) delivers a higher effective yield to a saver, or a higher effective cost to a borrower. Financial advertisements sometimes emphasise the nominal rate because it looks the same across products, while the effective rate is the number that actually determines how much you earn or pay over a year — always ask which figure is being quoted.

• Principal (P): ₹1,09,00,000
• Nominal annual rate: 2%
• Effective annual rate: 2.00%
• Time: 14 years
• Compounding frequency: 1 per year
• Total compound interest: ₹34,82,319
• Maturity (P + interest): ₹1,43,82,319

For contrast only, simple interest on the same P, R, T would total about ₹1,39,52,000 — roughly ₹4,30,319 higher with compounding under these assumptions.

A popular shortcut for estimating how long money takes to double under compounding is the Rule of 72: divide 72 by the annual rate. At 2%, that gives an estimated doubling time of about 36.0 years. Running the exact calculation with this calculator's own compounding logic (rather than the approximation) gives a doubling time of about 35.0 years — the Rule of 72 is a fast mental-math approximation, not an exact formula, and its accuracy is best for rates roughly in the 6-10% range; it drifts further from the exact answer at very low or very high rates.

Compare this to simple interest, where doubling time is 100 ÷ R rather than approximately 72 ÷ R — a clear, concrete illustration of why compounding reaches the same milestone meaningfully faster than simple interest at the same nominal rate. Some people also use "Rule of 114" (for tripling) or "Rule of 144" (for quadrupling) as extensions of the same mental-math shortcut, though these are used far less often than the Rule of 72.

Suppose the goal is a maturity of about ₹2,88,00,000 in 14 years at the same 2% nominal rate, compounded 1 time(s) a year. Working the compound interest formula backwards, the principal required today is approximately ₹2,18,26,800 — noticeably more than the ₹1,09,00,000 used in the base scenario, since the target here is roughly double the base maturity.

The two levers that close this gap are a longer tenure (giving compounding more time to work) or a higher nominal rate (which typically means a riskier product) — useful to keep in mind if the required principal above is more than you currently have available to invest today.

1. Start with the principal: ₹1,09,00,000.
2. Note the nominal annual rate: 2%.
3. Note the compounding frequency: 1 time(s) per year, meaning the period rate applied each time is 2.000%.
4. Note the tenure: 14 years, meaning there are 14 total compounding periods.
5. Apply the period rate repeatedly: after the first period, the balance grows to about ₹1,11,18,000; after all 14 periods, it compounds to ₹1,43,82,319.
6. Subtract the principal to isolate the interest earned: ₹1,43,82,319 − ₹1,09,00,000 = ₹34,82,319.
7. Compare against simple interest on the same numbers: ₹1,39,52,000 total, a difference of about ₹4,30,319 attributable purely to compounding.

Holding principal, annual rate, and tenure constant, increasing compounding frequency typically raises maturity when the nominal annual rate is unchanged — the table shows the pattern for common n values.

This calculator computes pre-tax figures. In practice, interest from most compounding deposits — bank fixed deposits, recurring deposits, and similar instruments — is added to your total income and taxed at your applicable income-tax slab rate, not at a flat capital-gains rate. On the illustrative interest of about ₹34,82,319 here, the actual tax owed depends entirely on your total taxable income and which slab you fall into — there is no single flat rate to apply.

• TDS: banks generally deduct tax at source once interest from a single bank (across branches) crosses a threshold in a financial year (a higher threshold applies for senior citizens). TDS is not the final tax — you settle the balance (refund or additional payment) when filing your return.
• Form 15G/15H: if your total income is below the taxable threshold, you can submit Form 15G (or 15H for senior citizens) to request that the bank not deduct TDS, though the interest itself remains taxable if your income later crosses the threshold.
• PPF and certain government schemes: some specific instruments (like PPF) enjoy tax-exempt interest under the EEE (exempt-exempt-exempt) structure — this general compound interest calculator does not distinguish between taxable and tax-exempt products, so always check your specific scheme's tax treatment.

Looking at the frequency table above, the gap between annual and monthly compounding at the same nominal rate is real but often modest for shorter tenures and typical retail interest rates — it widens as the rate and tenure both increase. For a saver, more frequent compounding is always at least as good, never worse, at an identical nominal rate. For a borrower, the reverse is true: more frequent compounding on an outstanding loan balance increases the effective cost of borrowing, even if the quoted nominal rate looks the same across offers.

This is why comparing loan or deposit offers purely on the quoted nominal rate can be misleading — always ask for (or compute) the effective annual rate before deciding, especially when comparing offers with different stated compounding frequencies.

Different tenures (same P, R, frequency)

Different rates (same P, T, frequency)

Different principals (same R, T, frequency)

The ₹1,43,82,319 maturity figure above is in nominal rupees — it does not account for inflation eroding purchasing power over the 14-year period. As a rough illustration, if inflation averaged 6% a year over that period, the real (inflation-adjusted) value of ₹1,43,82,319 in today's purchasing power would be approximately ₹63,61,314 — meaningfully less than the nominal figure, especially over longer tenures. This is why comparing a deposit's quoted rate against a plausible inflation assumption (rather than just looking at the rupee maturity value) gives a more realistic sense of how much richer, in real terms, an investment actually makes you.

A rough "real rate of return" can be approximated as (nominal rate − inflation rate). If the nominal rate here is 2% and inflation runs around 5-6% annually, the approximate real return is only a few percentage points — worth keeping in mind before treating a headline maturity figure as guaranteed purchasing power in the future. This is one reason many long-term investors look beyond pure fixed-rate compounding products toward growth assets, accepting more volatility in exchange for a better chance of outpacing inflation.

• Confusing nominal and effective rate. A 2% nominal rate compounded 1 time(s) a year actually yields about 2.00% effectively — using the nominal figure directly in a year-over-year growth comparison understates the real return.
• Using the wrong period rate. When compounding n times a year, the rate applied each period is R/(100n), not R/100 — a common source of error when working the formula by hand.
• Assuming the Rule of 72 is exact. It is a fast approximation, most accurate near 6-10% annual rates; for precise answers (loan comparisons, large sums), use the exact formula or this calculator.
• Ignoring tax on interest income. Interest from most compounding deposits in India is taxed at your slab rate, and banks may deduct TDS above a threshold — the maturity figure here is pre-tax.
• Forgetting that real products rarely compound with textbook precision. Actual bank compounding conventions, day-count rules, and minimum balance requirements can create small differences from this idealized formula.
• Overlooking inflation entirely. A large nominal maturity value can still represent a modest real (inflation-adjusted) gain — always sanity-check the nominal figure against a reasonable inflation assumption for long-horizon goals.
• Comparing rates without matching tenure and frequency. Two offers are only truly comparable once both the compounding frequency and the time horizon are the same, or converted to the same effective annual basis.

This calculator models pure textbook compound interest. Real Indian savings products build on the same idea but add their own rules:

Use this calculator to understand the mechanics of compounding, then check the actual scheme's compounding frequency, tax treatment, lock-in period, and premature withdrawal rules before comparing products head-to-head. Many banks also offer a non-cumulative FD option where interest is paid out periodically rather than reinvested — that structure behaves more like simple interest from the depositor's perspective, since the payout no longer compounds within the same account once withdrawn, unless the depositor separately chooses to reinvest each payout elsewhere.

• Students learning the difference between simple and compound interest for school or competitive exams.
• Savers comparing FD or RD offers that quote the same nominal rate but different compounding frequencies, to see which delivers a higher effective yield.
• Anyone estimating long-term growth of a lumpsum, retirement corpus, or savings goal using a simple, transparent formula before consulting more detailed, product-specific tools.
• Borrowers checking how quickly unpaid interest compounds on products like credit cards, where understanding the mechanics helps illustrate why balances can grow quickly if left unpaid.
• Anyone comparing two deposit or loan offers that quote the same nominal rate but different compounding frequencies, to work out which one is genuinely better once the effective annual rate is accounted for.

₹1,09,00,000 at a nominal 2%, compounded 1 time(s) a year for 14 years, is projected to reach about ₹1,43,82,319 — an effective annual rate of roughly 2.00%. The core idea worth internalising is that compounding accelerates growth by letting interest earn its own interest, so small differences in rate, frequency, or tenure produce outsized differences in outcome over long horizons. Use the sensitivity tables above to see exactly how much each lever matters, and remember that the same mechanism that builds wealth for savers also compounds unpaid debt for borrowers just as quickly — understanding this formula thoroughly cuts both ways, for saving and for borrowing alike.

All figures are computed live from the principal, nominal rate, tenure, and compounding frequency you entered, using the standard formula A = P × (1 + R/(100n))^(n×t). Sensitivity tables recompute the same formula at nearby tenure, rate, and principal values. The Rule of 72 estimate and exact doubling time are both derived from your specific rate. Nothing here reflects a specific bank or investment product's actual terms, TDS treatment, or compounding convention — verify against the actual scheme documentation before relying on these numbers for a real decision.