Personal Budgeting
See where your money goes, what is left over and what could change.
Open Tool: Personal BudgetingEXPLORE THE NUMBERS
Money & Financial Decisions
Money decisions can feel complicated because several things are usually happening at once — interest, time, inflation, repayments, investment growth and everyday living costs.
These tools are designed to help you explore the numbers before making an important financial decision. Change the assumptions, try different scenarios and see how the outcome changes.
You do not need to be an accountant or investment expert. Each calculator explains what the numbers mean in plain English.
Free to explore · No account needed · Calculations stay in your browser · Business scenarios can be saved on this device
Rule of 72
Explore roughly how long an investment could take to double.
Open Tool: Rule of 72KiwiSaver Growth
Explore how time, contributions, returns and fees affect your balance.
Open Tool: KiwiSaver GrowthRetirement & the 4% Rule
Translate an income gap into an illustrative savings target.
Open Tool: Retirement & the 4% RuleLoan & Mortgage
Understand repayments, interest and the effect of paying a little extra.
Open Tool: Loan & MortgageOwn vs Rent & Invest
Compare home equity with investing while renting, on equal cash budgets.
Open Tool: Own vs Rent & InvestBusiness Modelling
Explore how changes to sales, costs, borrowing and working capital affect your business’s profit, cash and financial health.
Open Tool: Business ModellingGoodwill Funnel
Explore the qualitative factors affecting business goodwill through Greg Harrison’s framework and nine component guides.
Explore Goodwill FunnelArticles
Articles by our founder.
Read ArticlesStrategy Inspiration Calculator
This is the strategy equivalent of a doodle pad to catch ideas. Sometimes, when thinking about an upcoming strategy session, you need a spark. That is what this tool is for. It is based on Greg Harrison’s Goodwill Funnel theory of strategy.
Spark a strategy ideaLearn the basics
A little understanding makes the numbers more useful.
Compound interest
Growth can earn further growth. Leaving returns invested gives compounding more time to work, but market investments can fall as well as rise.
Interest rates
A borrowing rate determines part of the cost of a loan. An investment return assumption is not the same as a guaranteed deposit rate. Small percentage changes can make a big difference over many years.
Inflation
Inflation means money buys less over time. These calculators show nominal dollars: a large future balance may have substantially less spending power than the same amount today.
Investment risk
Returns are uncertain. You can lose capital, and the timing of losses matters—particularly when withdrawing money. Higher expected returns generally involve accepting greater risk.
Diversification
Spreading investments across assets, industries and places reduces reliance on any one investment. It cannot eliminate all risk or guarantee a profit.
Mortgage principal vs interest
Principal is the amount still borrowed. Interest is the charge for borrowing it. Early in a long loan, more of a repayment commonly goes to interest; later, more goes to principal.
Cashflow
Cashflow is money coming in and going out over a period. Owning valuable assets does not necessarily leave enough cash to pay this month’s bills.
KiwiSaver
KiwiSaver is a retirement savings scheme with access rules and potentially employer and government contributions. Fund risk, fees, tax, eligibility and current rules matter. Check your provider and Inland Revenue.
Retirement income
Retirement spending may be funded by NZ Super, pensions, investments and other income. A withdrawal rule is a planning shortcut. It cannot ensure money will last throughout retirement.
Emergency savings
Accessible savings can help cover unexpected costs without borrowing or selling long-term investments at a bad time. A suitable amount depends on your bills, income stability and responsibilities.