Entrovix AI

Compound Interest Calculator

Growth with regular contributions, shown three ways: the headline figure, what it is worth after inflation, and what is left after tax on the gain.

Runs in your browser — nothing is uploaded

Investment details
₹
₹

Leave at 0 for a lump sum only

% per year
years

Effective annual rate: 12.68%

% per year
%

12.5% is the current long-term capital gains rate on equity

Maturity value

₹5,99,580

₹1,00,000 invested, ₹4,99,580 gained

What that will actually buy

₹2,24,127

In today's money, after 6% inflation and 12.5% tax

Inflation and tax take 62.62% of it

The headline is ₹5,99,580, but ₹62,448 goes in tax and inflation erodes the rest to ₹2,24,127 in today's money. Your real rate of return is 5.66% a year, not 12%.
Effective annual rate12% compounded monthly
12.68%
Time to doubleExact, not the rule-of-72 estimate
5.81 years
Tax on the gain
₹62,448
Value after tax
₹5,37,133
Why use it

Built to be genuinely useful

Inflation-adjusted

₹50 lakh in twenty years is not ₹50 lakh. See what it will actually buy in today's money.

Tax on the gain

Long-term capital gains come off the top. The after-tax figure is the one you can spend.

Any compounding frequency

Yearly through daily, with the effective annual rate shown so you can compare quoted rates honestly.

Monthly contributions

Model a lump sum, a monthly addition, or both — with a year-by-year table you can export.

How it works

Three steps

  1. 1

    Enter your starting amount and anything you plan to add each month.

  2. 2

    Set the expected return, the term and how often interest compounds.

  3. 3

    Leave the real-value switch on to see the figure after inflation and tax.

The maturity figure is the least useful number on the page

Every compound interest calculator shows you a large number at the end of a long period, and the number is real. It is also close to meaningless on its own, because it is quoted in rupees that will not buy what rupees buy today.

₹1 lakh growing at 10% for twenty years becomes ₹6.7 lakh. At 6% inflation, that ₹6.7 lakh buys what ₹2.1 lakh buys now. The investment has roughly tripled your purchasing power, which is a genuinely good outcome — but it is a third of the headline, and the headline is what people plan around.

Then the gain is taxed. Long-term capital gains on equity currently run at 12.5%, and that comes off before you can spend anything. The three figures together are the answer; the first one alone is a sales pitch.

Compounding frequency and the effective rate

12% compounded quarterly is not 12% a year — it is 12.55%. Compounded monthly it is 12.68%, and daily it is 12.75%. The quoted rate and the rate you actually receive are different numbers, and which one a provider advertises tends to depend on which is larger.

The effective annual rate shown beside the frequency selector is the honest comparison figure. When you are choosing between products quoting different compounding periods, compare those rather than the headline rates.

Doubling time, and why the rule of 72 is only approximate

The rule of 72 says money doubles in 72 ÷ rate years — at 10%, about 7.2 years. The exact figure is 7.27 years, and the approximation drifts further at higher rates: at 20% the rule says 3.6 years against a true 3.8.

The figure shown here is the exact one, calculated from the logarithm rather than the shortcut. Over a single doubling the difference is small; over four or five it is not.

What the projection cannot tell you

A constant annual return is a modelling convenience, not a description of markets. Real returns arrive unevenly, and the order they arrive in matters enormously if you are drawing money out along the way — a bad first five years does far more damage than a bad last five, even at the same average.

Treat the output as a planning figure for comparing options, not a forecast. It answers 'how much difference does two more years make' well, and 'how much will I have' only as well as your return assumption deserves.

FAQ

Questions people ask

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