About CozyCalcs

What this is

CozyCalcs is a small, independent collection of calculators for the money and life decisions that keep coming round: what a loan really costs over its life, what a pay packet comes to after tax, what a price tag costs in hours of your working life, what a habit becomes if it is invested instead, and who is paying for the pizza.

Everything here is free, needs no account, and runs in the browser you already have. Nothing you type is sent to a server: every figure you enter stays on your device. The one thing measured is anonymous visit counting through Google Analytics, so it is possible to see which calculators are worth improving. The privacy policy sets out exactly what that records, and what it never sees.

Why the calculators are shaped the way they are

Most calculators take your numbers, do something invisible, and hand back a figure you simply have to trust. Each page here does the opposite. It says why you might use it, what the maths is — formulas and all — and then answers the questions people actually ask about it.

Where a number depends on an assumption, the page says so in plain words rather than burying it: the calculator assumes one fixed interest rate for the life of the loan, no fees unless you enter them, no tax on the growth, no inflation. Nothing here is a black box, and if you want to check a figure by hand, the working is on the page.

Where the numbers come from

• The pay calculator uses the ATO's rates for the financial year you choose, the 12% super guarantee, the Medicare levy and its low-income thresholds, the Medicare levy surcharge and the marginal HELP repayment system. The 2026–27 Medicare low-income threshold has not been published yet, so that one figure is the calculator's own assumption and the page says so.
• The loans use the standard amortisation formula — the same one every lender uses to work out a repayment — at the rate and term you enter.
• Everything else is arithmetic you can follow: a price divided by the number of uses, a price divided by an hourly rate, a balance grown at a rate you choose, a set of bills turned into a year and then split.
• The Budget tool keeps your entries in your own browser, with a backup file you control. It has no server and no account, which is why nobody — including this site — can see your numbers.

What is not here

No advice. Every tool is an estimate and a teaching aid, not financial, tax, legal or credit advice, and none of them can know your circumstances: the fees your lender charges, the deductions you can claim, the rate you will actually be offered. Each page lists the assumptions it makes, and the terms of service say the same thing at more length.

It is a site made in Australia, for Australian numbers first — dollars, the ATO's brackets, the Medicare levy — with a few just-for-fun tools that work anywhere. It is looked after by one person, with the odd calculator added when it is finished and checked.

Say hello

New calculators go up as they are finished. The quickest way to hear about them is to follow along on Instagram or TikTok.

Found a figure that looks wrong, or a calculator you wish existed? That is the most useful message this site can get — the contact page says where to send it and what to include.