About OzCalc

Why this site exists

Most calculators on the internet are built for somewhere else. They assume a tax year that starts in January, quote fuel in miles per gallon, add a sales tax that is not GST, and have never heard of the superannuation guarantee or a HELP debt. For an Australian question that makes them anywhere from mildly annoying to plainly wrong.

OzCalc starts from the Australian case. The income year runs from 1 July to 30 June. Pay converts across weekly, fortnightly and monthly cycles using PAYG withholding — the same method as a payslip. Rent is advertised weekly and converted with a 52-week year. Fuel is litres per 100 kilometres. Business days respect the public holidays of the state you choose, because those are set state by state.

There are currently 55 calculators, 21 guides and 5 collections. A calculator produces a working result. A guide explains the rule without any inputs to fill in. A collection walks through several tools in the order a real decision needs them.

How OzCalc is run

OzCalc is independently operated. It is not a government service, bank, lender or tax agent, and it is not a content marketplace. Calculators, explanations, source reviews and correction reports are handled as one product by the same small team, so a threshold quoted in a guide and a threshold used in a result cannot silently drift apart.

You do not need an account. The numbers you type stay in your browser — they are not sent to a server or saved to a profile. Favourites and recently used tools are stored on this device only.

What has to be on a page before it is published

A public calculator has to produce a correct result and include a plain-English meaning, the formula and its variables, the assumptions it made, a worked example with real numbers, answered questions, and a cited source. Empty or unfinished routes are not published. Thin doorway pages — city clones, appliance clones, the same calculator repeated for every suburb — are not published either. That rule is enforced in the codebase: the test suite fails the build if any of those pieces is missing.

Where a result depends on a regulated figure, the page names the source, the period it applies to, and the date it was last reviewed. The editorial policy sets out which sources we treat as authoritative — the ATO, Fair Work, ASIC’s Moneysmart, state tenancy authorities, the National Measurement Institute — and how a correction is handled when a figure moves.

What a result is, and what it is not

A result is an estimate produced by applying a published method to the figures you enter. It cannot know your deductions, your award, your lender’s fees or your energy tariff. Each page lists what it assumes so you can see the gap between the estimate and your actual situation.

• Tax and super tools apply ATO rates to a simple, steady resident case unless you turn extra options on.
• Loan tools assume a constant rate for the whole term and ignore application fees, LMI and stamp duty unless the page says otherwise.
• Work tools apply the hours and multipliers you type. They do not look up your modern award.
• Date tools follow the civil calendar or the public holidays of the state you choose. A contract that defines “business day” differently wins.

The disclaimer is the full statement of those limits. If a decision is important, confirm it with the official source or a qualified professional.

Guides, collections and the catalogue

The guides exist because a calculator answers “what is the number” and most people also need “why is it that number”. Each guide is written against the same dataset the calculators use, so a Medicare threshold or a superannuation guarantee rate cannot be one figure in the article and another in the tool.

Collections are routes through a task, not extra copies of the tools. Buying a home, comparing two job offers and naming the right income year all need several calculations in a deliberate order. Categories on the calculator index are a filing system for when you already know what you are looking for.

Privacy and funding

The site is free and is funded by advertising. Advertisers have no input into which calculators exist, what the explanations say, or what a result shows. Ads are kept out of inputs and results so an advertisement cannot be mistaken for part of a calculation.

The site uses Google Analytics and Vercel Analytics for traffic, Vercel Speed Insights for page speed, plus Google AdSense Auto ads and profitableratecpmnetwork.com scripts for support. The privacy policy lists those services and the choices available to you. Advertising never changes a calculator result.

Corrections

If a rule has changed, an explanation is unclear or a result looks wrong, use the contact page or email hello@ozcalc.com. The most useful report names the calculator and the inputs that produced the issue. Please do not include private financial or identifying information — we do not need it to reproduce an arithmetic problem.

Substantive corrections are made in the underlying dataset, which updates every calculator and guide that depends on that figure along with the review date shown on the page. We do not quietly change a number and leave the date untouched.

This page was last updated 7 September 2026. The site was last deployed 7 September 2026.