New Zealand·Calculators·Compound interest

Compound interest calculator

Compound interest: A = P(1 + r/n)^(nt) + PMT x [(1 + r/n)^(nt) - 1] / (r/n). Growth is the final balance minus what you put in.

Your numbers

Starting amount

$NZD

Added each month

$NZD / month

Annual return

% p.a.

Years

years

Balance after 10 years:

$70,348

$17,348 of that is growth

You put in$53,000

Growth$17,348

Final balance$70,348

Months compounded120

User-supplied annual nominal return compounded monthly. Monthly contributions are added at the end of each month. No tax, fees, inflation, withdrawals or variation in return. Scenario only: the supplied return is not a forecast or guaranteed rate.

Source: your own figures · no market rate assumedThe arithmetic is the same in every country

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How it works

Compounding means this month's growth earns growth of its own next month. The longer the run, the more of the final balance comes from growth rather than from what you put in.

The return you enter is a scenario, not a forecast. Real returns vary year to year, and a smooth average hides that.

Common questions

Is the return guaranteed?

No. The figure you enter is applied evenly every month. Real investments do not behave that way, and a bad first few years costs more than the same years later on.

Does this account for tax or fees?

No. Both reduce the real balance. Subtract your fund's fee from the return you enter to get closer.