Calculate.co.nz

Calculate.co.nz Calculators API

New Zealand tax, money and health calculations. Each one is a port of the calculator of the same name on calculate.co.nz, and the website is the reference: where the two disagree the API is wrong until proven otherwise, and the test suite fails the build.

GitHub OpenAPI

Operations 46

POST /v1/paye NZ take-home pay after PAYE #
POST /v1/gst Add or remove NZ GST #
POST /v1/bmi Body mass index and healthy weight range #
POST /v1/mortgage Mortgage repayments and lifetime totals #
POST /v1/annual-leave Annual leave balance projected forward #
POST /v1/fuel-cost Fuel cost of a trip and of regular driving #
POST /v1/tax-refund NZ income tax refund or bill for a year #
POST /v1/gpa Grade point average on the NZ nine point scale #
POST /v1/hourly-to-salary What an hourly rate is worth as a salary #
POST /v1/work-hours Total hours from a timesheet, and what they pay #
POST /v1/bonus-tax Tax on a bonus or commission payment #
POST /v1/power-tower Power tower (tetration), a^^n #
POST /v1/parental-leave NZ paid parental leave payment and shortfall #
POST /v1/net-to-gross The gross salary needed to take home a given amount #
POST /v1/final-pay What is owed on leaving a job, gross #
POST /v1/secondary-tax Secondary tax code for a second income, and the year-end position #
POST /v1/pro-rata-salary A full-time salary scaled to part-time hours #
POST /v1/lump-sum-tax PAYE on a redundancy or lump sum, by IRD's rate table #
POST /v1/working-for-families Working for Families entitlement after abatement #
POST /v1/road-user-charges Road user charges for an EV, diesel or plug-in hybrid #
POST /v1/electricity-cost Household electricity cost by region and appliance #
POST /v1/ncea-rank-score University rank score (Auckland, Massey, Otago method) from NCEA, and an… #
POST /v1/vehicle-loan Vehicle loan repayments and what the interest costs #
POST /v1/energy-expenditure BMR, TDEE, a calorie target and the macros to hit it #
POST /v1/kiwisaver KiwiSaver balance projected to retirement #
POST /v1/fbt Fringe benefit tax on a vehicle, a low-interest loan or another benefit #
POST /v1/redundancy-entitlement What is owed on redundancy in New Zealand, mandatory and contractual #
POST /v1/grocery-budget A weekly grocery budget for a named New Zealand household #
POST /v1/contractor-vs-employee Contracting against salaried employment, on what you actually keep #
POST /v1/benefit-entitlement Weekly main benefit, abatement and Accommodation Supplement #
POST /v1/schedular-payments Withholding tax on a schedular payment to a contractor #
POST /v1/acc-weekly-compensation ACC weekly compensation, with the floor and the ceiling both shown #
POST /v1/sick-leave Sick leave entitlement and balance under the Holidays Act #
POST /v1/tax-code The right New Zealand tax code, and why #
POST /v1/paye-due-dates When an employer must pay PAYE and file the pay run #
POST /v1/depreciation Straight line or diminishing value depreciation, year by year #
POST /v1/minimum-wage NZ minimum wage on a date, and take-home pay #
POST /v1/overtime-pay Weekly pay with time and a half, double time and time and a quarter #
POST /v1/citizenship-presence NZ citizenship by grant: the 1,350 and 240 day presence test #
POST /v1/standard-drinks How many NZ standard drinks are in a drink #
POST /v1/ncea-grade NCEA result: credits, co-requisite, certificate, endorsements and University… #
POST /v1/public-holidays New Zealand public holidays for a year, and the next one #
POST /v1/business-days New Zealand working days between dates, or N working days from a date #
POST /v1/holiday-pay Holiday pay under the Holidays Act: leave, 8% PAYG, public holidays, termination #
POST /v1/rates-water 2026/27 council rates and water charges for one house #
POST /v1/import-duty Customs duty, GST and the goods levy on goods sent or shipped to New Zealand #

Specifications

⚙
OpenAPI
https://artifacts.apis.io/calculate-co-nz/openapi/calculate-co-nz-calculators-api-openapi.yml

Schemas & Data

📊
JSONSchema
https://artifacts.apis.io/calculate-co-nz/json-schema/calculate-co-nz-holiday-pay-request-schema.json
📊
JSONSchema
https://artifacts.apis.io/calculate-co-nz/json-schema/calculate-co-nz-minimum-wage-response-schema.json
📊
JSONSchema
https://artifacts.apis.io/calculate-co-nz/json-schema/calculate-co-nz-final-pay-request-schema.json
📊
JSONSchema
https://artifacts.apis.io/calculate-co-nz/json-schema/calculate-co-nz-import-duty-response-schema.json
📊
JSONSchema
https://artifacts.apis.io/calculate-co-nz/json-schema/calculate-co-nz-ncea-rank-score-response-schema.json
📊
JSONSchema
https://artifacts.apis.io/calculate-co-nz/json-schema/calculate-co-nz-electricity-cost-response-schema.json

Other Resources

🔗
APIsJSON
https://artifacts.apis.io/calculate-co-nz/apis.yml

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OpenAPI Specification

calculate-co-nz-calculators-api-openapi.yml Raw ↑ 
openapi: 3.2.0
info:
  title: Calculate.co.nz Calculators API
  description: 'Free access to New Zealand tax, KiwiSaver, mortgage and property calculations.

    No sign-up needed to start.


    **Anonymous calls are limited to 120 an hour per IP.** That is far more than

    a person or an assistant session will ever use, and less than a product needs.

    If you are building something, request a free key and send it as `X-API-Key`:

    it raises the limit to 5000 an hour and means we can tell you before anything

    changes. Keys are issued by hand, usually same day. Ask at contact@calculate.co.nz


    Every response carries `X-RateLimit-Limit`, `X-RateLimit-Remaining` and

    `X-RateLimit-Reset`. Over the limit returns `429` with `Retry-After`.


    **Every calculation is a port of the page of the same name on

    calculate.co.nz.** The website is the source of

    truth: rates come from `paye-data.php`, the same file the site''s own calculators

    read, and the test suite fails if the two ever disagree. Rates are reviewed

    twice monthly against IRD, RBNZ and Stats NZ.


    **Fourteen calculators have their own endpoint.** For anything else, call

    `POST /v1/find-calculator` with a plain-language question and it will return the

    right page from the whole site.


    **`GET /v1/rates` publishes the underlying New Zealand reference data**: tax

    brackets, the ACC earner levy and its cap, student loan thresholds, KiwiSaver

    settings and benefit rates. Each figure carries the date it took effect, where

    it was read from, and when it was last checked against the issuing body, with

    `verified_on` left null rather than guessed where that check has not been done.

    Filter by `review_cycle=annual-1-april` to get everything that moves on 1 April.


    These are the same figures the calculators consume, and an automated harness

    drives the live pages on the website in a browser and compares their answers to

    this API. A wrong rate breaks a visible page rather than sitting unnoticed in a

    data feed.


    **Every response carries a `disclaimer`, and it is not boilerplate to strip

    out.** These are estimates under stated assumptions, not financial, tax or legal

    advice. `POST /v1/paye` also returns an `assumptions` block naming the tax year

    and every rate used, so a stored result can be audited later against the rules

    that applied on the day.


    The same calculators are available to AI assistants over the Model Context

    Protocol at `https://mcp.calculate.co.nz/mcp`.


    Questions, or something wrong: contact@calculate.co.nz'
  termsOfService: https://www.calculate.co.nz/terms.php
  contact:
    name: Calculate.co.nz
    url: https://www.calculate.co.nz/contact.php
    email: contact@calculate.co.nz
  version: 1.16.0
servers:
- url: https://api.calculate.co.nz
  description: Production
tags:


# --- truncated at 32 KB (426 KB total) ---
# Full source: https://artifacts.apis.io/calculate-co-nz/openapi/calculate-co-nz-calculators-api-openapi.yml