KiwiTools guide
How KiwiTools results work
We keep formulas, assumptions, external data and limitations visible so you can understand what drives a calculation or finder result.
PAYE and income calculations
For the 2027 tax year, income is annualised and each portion is taxed using the applicable progressive bracket. ACC is calculated separately up to maximum liable earnings. Selected KiwiSaver and student-loan deductions are then applied. Pay converters and average-daily-pay tools use the work periods and earnings entered rather than inferring an employment entitlement.
Electricity and solar calculations
Appliance cost uses watts divided by 1,000, multiplied by usage time, duty cycle and the entered price per kWh. Bill estimates separate variable usage, daily charges, other charges, discounts and GST. Solar payback models entered installation cost, generation, self-use, export and degradation assumptions; it is not a forecast or quote.
Mortgage and property calculations
Mortgage results use the standard amortising-loan formula with the entered principal, rate, frequency and term. Property tools use entered deposits, buying costs, council rates, rent, vacancy and expenses. They do not determine lending approval, KiwiSaver eligibility, a council assessment or a property-specific market value.
Transport and comparison calculations
Fuel cost uses distance, fuel economy and pump price. RUC uses the selected rate and distance units. EV, mobile-plan and flight comparisons place entered alternatives on a common annual, trip or ownership-period basis. Prices, fees, resale values and inclusions remain assumptions unless the page identifies an official rule.
Outdoor finders and place records
Approved outdoor slugs come from validated catalogues with record-level modification dates and fixed quality gates. Depending on the category, a detail page uses a recently cached location record or a validated local snapshot. Last-known-good records prevent a temporary external outage from emptying a sitemap or established page. Alerts and forecasts update separately where available. Access rules, bookings and closures can change, so every result remains a planning aid rather than permission to travel or confirmation that a place is suitable.
Everyday checkers and planners
The annual-leave planner combines the selected work pattern with maintained public-holiday and regional-anniversary dates. The school-zone checker matches an address location against mapped enrolment-zone data and flags boundary uncertainty. School-zone results must be confirmed with the school or Ministry of Education.
Browser calculations and external services
Calculator inputs and results are normally processed in the browser. Features that require external data, including outdoor searches, address lookup and mapped school zones, can call a configured service. The contact form sends only the details the user chooses to submit to the KiwiTools contact service.
Rounding, updates and limitations
Calculations retain unrounded values where practical and format results for display in NZD or the relevant unit. Presets and finder records are starting points, not current offers, forecasts or recommendations. Outcomes and place conditions can differ because rules, rates, dates, external data and real-world circumstances change.