Financial Glossary
Compound Interest
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest, which is calculated only on the principal, compounding allows your money to grow exponentially over time. The frequency of compounding (daily, monthly, annually) affects the total growth.
Example
If you invest $10,000 at 7% annual return compounded yearly, after 30 years you would have approximately $76,123 without adding any additional money. With monthly contributions of $500, the same investment would grow to approximately $611,729. This exponential growth is why starting to invest early is so powerful.
Frequently Asked Questions
Why is compound interest powerful?
Compound interest creates exponential growth because you earn returns on your returns. Over long periods, the majority of growth comes from compounding rather than the initial principal. Starting early maximizes this effect.
How does compounding frequency affect returns?
More frequent compounding (daily vs. annual) results in slightly higher returns. For example, $10,000 at 7% over 30 years yields $76,123 with annual compounding and $76,466 with daily compounding. The difference grows with larger amounts and longer time horizons.
Related Resources
Official Sources
New Zealand calculators use data from the following official government agencies:
- Inland Revenue (IRD) — Income tax brackets, KiwiSaver rules, and ACC levies.
- Stats NZ — Wage data, employment statistics, and cost of living indices.
- Reserve Bank of New Zealand (RBNZ) — Official cash rate and monetary policy data.
Methodology
Our New Zealand calculators follow tax brackets, KiwiSaver contribution rates, and ACC levies published by Inland Revenue (IRD). Economic data is sourced from Stats NZ. Mortgage calculations use RBNZ official cash rate and market averages. All figures are for educational purposes.
Data Sources
All tax brackets, contribution rates, and economic data used in our calculators are sourced from the official government publications listed above. Rates are updated at least annually to reflect the latest tax year and regulatory changes. Users should verify critical figures with official sources or qualified professionals.
Last updated: June 2026. Information may change; always verify with official sources.
Last Updated: June 2026 — Reviewed Against Official Sources