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Compound Interest Calculator NZ
Free compound interest calculator: see what a starting amount plus monthly savings grows to at daily, monthly, quarterly or yearly compounding, with a year-by-year table and the effective yearly rate (APY).
Your savings
After 10 years
$47,527
| You put in | $34,000 |
| Interest earned | $13,527 |
| Effective yearly rate (APY) | 5.12% |
Year by year
| Year | Put in | Interest | Balance |
|---|---|---|---|
| 1 | $12,400 | $567 | $12,967 |
| 2 | $14,800 | $1,287 | $16,087 |
| 3 | $17,200 | $2,165 | $19,365 |
| 4 | $19,600 | $3,212 | $22,812 |
| 5 | $22,000 | $4,435 | $26,435 |
| 6 | $24,400 | $5,843 | $30,243 |
| 7 | $26,800 | $7,446 | $34,246 |
| 8 | $29,200 | $9,254 | $38,454 |
| 9 | $31,600 | $11,277 | $42,877 |
| 10 | $34,000 | $13,527 | $47,527 |
Compound interest pays interest on your interest. The longer you leave it, the faster it grows: at 5% a year money doubles in about 14 years (the rule of 72: 72 ÷ rate). Interest is taxed at your resident withholding tax (RWT) rate before it reaches you.
Interest before tax and fees, at the same rate every year; monthly additions are made at the end of each month. Not legal, tax or financial advice. 🔒 Everything stays on your device.
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Questions people ask
How is compound interest calculated?+
Balance = amount × (1 + rate ÷ n)^(n × years), where n is how often interest is added. Monthly savings are added on top and earn interest too.
How long does it take to double my money?+
Divide 72 by the yearly rate: at 6% about 12 years, at 4% about 18 years.
Does compounding frequency matter much?+
A little: 5% compounded monthly is 5.12% a year. Regular saving and time matter much more.