Savings Calculator NZ: Grow Your Savings or Reach a Goal
Project how your savings could grow with regular deposits and compound interest, or work backwards from a target to calculate how much you need to save each week, fortnight, month or year.
Updated 4 July 2026 · Results are estimates before tax, fees and inflation
- Choose Grow my savings to estimate your future balance, contributions and interest earned.
- Choose Reach a savings goal to calculate the regular contribution needed to hit a target.
- Use the current annual rate for your own bank account. Savings rates can change and bonus rates may have conditions.
How to calculate savings with compound interest
Future savings balance:FV = Balance × (1 + rate ÷ n)^(n × years) + Contribution × [((1 + rate ÷ n)^(n × years) − 1) ÷ (rate ÷ n)]
Contribution needed for a goal:Contribution = (Goal − Balance × (1 + rate ÷ n)^(n × years)) ÷ [((1 + rate ÷ n)^(n × years) − 1) ÷ (rate ÷ n)]
n is the contribution frequency used for this estimate: 52 weekly, 26 fortnightly, 12 monthly or 1 annually. Contributions are treated as arriving at the end of each period.
Your savings details
Your projection
ProjectionCalculating your savings projection…
Illustrative projection based on a fixed rate and regular end-of-period contributions.
| Starting balance | $0 |
| Total contributions | $0 |
| Interest earned | $0 |
| Estimated final balance | $0 |
How this Savings Calculator NZ works
The calculator has two modes. Grow my savings adds your starting balance to all regular contributions, then applies compound interest over your chosen time period. Reach a savings goal reverses the calculation and estimates the contribution required to reach a target by a set date.
- The annual interest rate is divided across the selected contribution frequency for this estimate.
- Regular contributions are assumed to be made at the end of each selected period.
- The rate is assumed to stay fixed, even though real savings account rates can rise or fall.
- Results are shown before Resident Withholding Tax, account fees and inflation.
- Amounts are rounded to the nearest New Zealand dollar for readability.
How to use the Savings Calculator NZ
- Choose a calculation mode. Select whether you want to project savings growth or work backwards from a savings target.
- Enter your current balance and timeframe. Add the amount already saved and the number of years available.
- Enter your contribution or goal. In growth mode, enter your regular deposit. In goal mode, enter the amount you want to reach.
- Select your contribution frequency. Choose weekly, fortnightly, monthly or annual deposits.
- Enter your current account rate. Use the annual interest rate offered by your bank rather than relying on the example presets.
- Review the projection. Compare your starting balance, total deposits, estimated interest and final balance.
Things to know before relying on a savings projection
- Interest is taxable. New Zealand banks generally deduct Resident Withholding Tax from interest before it is paid to you, so your after-tax balance can be lower than this estimate.
- Savings rates can change. Unlike a fixed term deposit, an on-call savings rate may increase or decrease during your saving period.
- Bonus rates may have conditions. These can include minimum deposits, limits on withdrawals or account-balance requirements.
- Inflation reduces purchasing power. A future dollar may buy less than a dollar today, even when the account balance grows.
- Eligible deposits may be protected. New Zealand's Depositor Compensation Scheme can cover eligible deposits up to $100,000 per depositor, per deposit taker, subject to the scheme rules.
Savings Calculator vs Term Deposit Calculator
Use this calculator for an accessible savings account where you can keep adding money and the rate may change. Use the Term Deposit Calculator NZ when money is locked away for a fixed term at a fixed rate.
Savings Calculator NZ Frequently Asked Questions
Enter your current balance, regular contribution, saving frequency, timeframe and annual interest rate. The calculator grows the starting balance and each contribution using compound interest, then shows the estimated final balance and interest earned.
Yes. Select “Reach a savings goal”, enter your target amount, current balance, timeframe, contribution frequency and annual rate, and the calculator will estimate the regular contribution required.
Use the current annual interest rate for the exact savings account you hold or are considering. The preset buttons are only illustrative examples and are not live bank-rate quotes.
No. The calculator shows interest before Resident Withholding Tax. Your bank normally deducts RWT from interest, so the amount actually credited after tax may be lower.
No. Results are shown in future nominal dollars and do not adjust for inflation. The future balance may therefore have less purchasing power than the same dollar amount has today.
Yes. Use goal mode for a house deposit, emergency fund, holiday, vehicle or another target. Enter the amount required and the date by which you want to reach it.
The calculator assumes each regular contribution is made at the end of the selected weekly, fortnightly, monthly or annual period. Depositing earlier may produce a slightly higher balance.
No. A savings account normally allows deposits and withdrawals while its rate can change. A term deposit generally locks money away for a fixed period at a fixed rate and may use different interest-payment and tax settings.
Your bank may calculate interest daily, credit it monthly, change the rate, apply bonus-rate conditions, deduct tax or charge fees. Your contribution dates may also differ from the simplified schedule used here.
No. It provides a general mathematical estimate only and does not consider your tax position, financial goals, risk tolerance or personal circumstances.
This calculator provides a high-level estimate based on the figures and fixed annual rate you enter. It does not model changing interest rates, Resident Withholding Tax, fees, inflation or your personal circumstances. It is not financial advice. Consider checking the current product terms with the bank or speaking with a licensed financial adviser before making financial decisions.