Compound Interest Calculator (NZD)
Find out how much a lump sum, or a lump sum plus regular contributions, could grow to over time.
Why compounding frequency matters
Interest can be compounded annually, quarterly, monthly or daily. The more often it compounds, the faster your balance grows, because each compounding period earns interest on interest already earned.
The impact of regular contributions
Adding even a small monthly amount alongside your starting balance can meaningfully change your result over long periods, thanks to the same compounding effect working on every contribution you add.
Frequently asked questions
What's a realistic rate of return to use?
It depends on the investment type. Term deposits and savings accounts in NZ typically offer lower, more stable rates, while diversified share portfolios have historically offered higher average returns with more year-to-year variation.
Does this account for tax on interest?
No. In New Zealand, interest and investment returns are generally taxable (e.g. RWT on interest, or PIE tax rates on managed funds). This calculator shows gross growth before tax.
What does 'compounding frequency' change?
It changes how often earned interest gets added to your balance and starts earning its own interest. Daily or monthly compounding will produce a slightly higher result than annual compounding at the same stated rate.