Coast FIRE Calculator New Zealand

To use the Coast FIRE calculator in New Zealand, enter your age, your target retirement age, the yearly spending your KiwiSaver and investments must cover, and your current balances. The calculator gives your Coast FIRE number: the amount you need invested today so your money grows into a full retirement fund without more voluntary saving.

1. Enter your Current Age.
2. Set your Retirement Age. NZ Superannuation and full KiwiSaver withdrawals both start at 65. Use 65 unless you plan to stop earlier.
3. Enter Annual Spending in Retirement in today's dollars. Subtract the after-tax NZ Super you expect. Rates depend on whether you're single or in a couple and whether you live alone, so check the current rates at Work and Income.
4. Enter Current Invested Assets. Add your KiwiSaver balance, managed funds, ETFs, and shares (for example through Sharesies, InvestNow, or Kernel). Leave out your home and term deposits held as an emergency fund.
5. Enter your Monthly contribution. Add your KiwiSaver contribution, your employer's contribution after Employer Superannuation Contribution Tax (ESCT), and any regular investing outside KiwiSaver.
6. Check Advanced Settings. The Reserve Bank of New Zealand targets 1% to 3% inflation, with a focus on the 2% midpoint. A 2.5% inflation input adds a small buffer.

How to read your results

• Coast FIRE number: the balance you need today.
• Progress: your balance as a share of the Coast FIRE number.
• FIRE Nest Egg: the full fund needed at 65, in today's dollars.
• Coast Age: the age you can stop voluntary saving.
• Cash Freed: the yearly saving you get back once you coast.
• Real Return: growth after inflation.

Enter every amount in New Zealand dollars.

---

The calculator finds the fund you need at retirement to cover the gap above NZ Super, then discounts it by your after-inflation return. The discounted amount is your Coast FIRE number.

The formula

FIRE Nest Egg     = Annual Spending ÷ Safe Withdrawal Rate
Real Return (r)   = (1 + Growth Rate) ÷ (1 + Inflation Rate) − 1
Coast FIRE Number = FIRE Nest Egg ÷ (1 + r)^Years

Worked example

Aroha is 35, single, and plans to retire at 65. She expects to spend NZ$52,000 a year and receive about NZ$27,000 after tax from NZ Super, leaving a NZ$25,000 gap. She uses 6.5% growth, 2.5% inflation, and a 4% withdrawal rate.

1. FIRE Nest Egg: NZ$25,000 ÷ 0.04 = NZ$625,000
2. Real Return: 1.065 ÷ 1.025 − 1 = 3.90%
3. Growth factor over 30 years: 3.153
4. Coast FIRE number: NZ$625,000 ÷ 3.153 = NZ$198,202

Aroha has NZ$80,000 in KiwiSaver and a share portfolio, which puts her at 40%. Her KiwiSaver contributions plus her own investing total NZ$1,000 a month, so she reaches Coast FIRE at age 48. At NZ$600 a month, she wouldn't get there until 62.

Factors that change your result

• KiwiSaver contributions. The default employee and employer rates rose from 3% to 3.5% on 1 April 2026 and are set to reach 4% from 1 April 2028. Employer contributions keep flowing while you work, even after you stop voluntary saving.
• Tax. KiwiSaver funds are taxed at your Prescribed Investor Rate (PIR), up to 28%. Foreign shares above NZ$50,000 in cost fall under the Foreign Investment Fund (FIF) rules. Use a growth rate net of these taxes.
• NZ Super rules. NZ Super is not means-tested, but it has residency requirements. Partners each receive a lower couple rate.
• Early retirement. KiwiSaver is locked until 65 except for first-home or hardship withdrawals, so retiring earlier needs money outside KiwiSaver.
• Rounding. Results are rounded to whole dollars, contributions are added yearly, and Coast Age is shown in whole years.

---