Embed Australian calculators with one line of HTML

Twelve tax and finance calculators for your blog, brokerage site, HR portal or intranet. They run in the visitor's browser, stay on the current 2026-27 ATO and state revenue figures, and cost nothing.

No signup No API key No cookies Auto-resizing MIT loader

Two ways to embed

1. Plain iframe — works anywhere

<iframe src="https://calk-au.com/embed/pay-calculator/"
        width="100%" height="1050" style="border:0;max-width:720px"
        title="Pay Calculator — Calk-AU" loading="lazy"></iframe>

Paste into a WordPress Custom HTML block, a Squarespace code block, anywhere. Fixed height, so tall results can leave whitespace.

2. With the loader — resizes itself

<div data-calk-au="pay-calculator"></div>
<script src="https://cdn.jsdelivr.net/gh/CryptoAgent666/calk-au-widgets@v1.0.0/calk-au-embed.js" async></script>

The widget reports its height and the iframe follows. One script tag covers every widget on the page.

Live: pay calculator

This one is embedded with the loader — type a salary and watch the frame grow instead of scrolling inside itself.

Live: stamp duty, opened pre-filled

Same loader, with data-query passing a $750,000 first-home purchase in NSW.

Live: GST, pinned to light theme

Available calculators

pay-calculatorTake-home pay income-tax-calculatorIncome tax + Medicare gst-calculatorAdd or remove GST stamp-duty-calculatorTransfer duty, 8 states mortgage-repayment-calculatorRepayments + interest super-calculatorBalance at retirement hecs-help-calculatorHECS repayments pay-rise-calculatorWhat you keep from a raise salary-comparison-calculatorTwo offers compared fhss-calculatorFirst Home Super Saver compound-interest-calculatorCompound growth percentage-calculatorPercentages

Options

Attribute	Default	Purpose
`data-calk-au`	required	Calculator slug
`data-height`	per calculator	Starting height before the first self-report
`data-max-width`	`720px`	Responsive down to 320px
`data-theme`	system	`light` or `dark`
`data-title`	calculator name	iframe title for screen readers
`data-query`	—	Pass-through query, e.g. `pay=90000&hecs=1`

Why the numbers stay right

Australian rates move every July, and half of them move again mid-year. The second marginal bracket fell to 15% on 1 July 2026, super guarantee hit 12%, HECS thresholds reindexed, and every state rewrote its stamp duty and registration schedules. Calk-AU tracks more than a thousand government-set values with weekly source monitoring and quarterly re-verification against primary sources, so an embedded widget updates the moment a rate changes. You maintain nothing.

Terms

Free for commercial and personal use, client sites included. Keep the "Powered by Calk-AU" line inside the widget visible, and don't present results as financial advice. The loader script is MIT licensed; the calculators stay hosted by Calk-AU.