About gazza.ltd
Free calculators and everyday tools, built to show their working.
The magpie is a collector. Not of shiny trinkets — that turns out to be folklore rather than fact — but of genuinely useful things, cached away and remembered for when they're needed.
Why a magpie
The bird has a reputation for stealing anything that glitters, and it's a good story. It just isn't true. When researchers at the University of Exeter tested it properly, offering both captive and wild magpies shiny objects alongside dull ones, the birds showed no particular interest in the shiny ones and were mostly wary of anything unfamiliar. The myth seems to survive because we notice the times a magpie picks up a ring and forget the far more numerous times it picks up a twig.
What magpies genuinely do is cache. They hide food in scattered places and remember where they put it. They're also one of the very few species to recognise themselves in a mirror, which puts them in select company.
That felt like the right emblem for this site: a collection of small, useful things, kept somewhere you can find them again. And a bird whose best-known trait falls apart the moment anyone checks — which is a decent argument for showing your working.
What this is
gazza.ltd is a growing collection of single-purpose calculators and utilities — mortgages and tax, word games, text tools, PDF tools, with more added over time. Every tool is free, requires no sign-up, and runs entirely in your browser.
How the tools work
Each calculator explains the method it uses underneath the tool itself, with a worked example using real numbers, so you can check a result rather than just trust it. The finance tools go further: the tax rates they use are listed with the official source they came from and the date they were last checked.
Nothing you type is sent anywhere or stored. The PDF tools are the clearest case — your files are processed on your own device and never uploaded, which is not true of most online PDF services. See the privacy policy for the full detail.
Terms of use
The calculators on this site are provided for general informational purposes only. They are not financial, legal, medical or professional advice, and results should be treated as estimates rather than guarantees. Formulas and reference data such as tax bands are kept as accurate and current as we can manage, but you should verify anything you're relying on for an important decision with a qualified professional or an official source.
The site is provided as-is, without warranty of any kind. We aren't liable for decisions made using the figures these tools produce.
Advertising
This site is supported by display advertising, which is what keeps every tool free to use. See the privacy policy for how advertising cookies work and how to opt out of personalised ads.
Tell us what's wrong with it
If a calculator gives a figure you think is incorrect, that's worth knowing about — send the numbers you entered and what you expected, and it'll get checked against the source. The same goes for a tool that behaves oddly on your phone, or one you wish existed and doesn't.
Email hello@gazza.ltd.