About CalculatorHub
You came here with a question. That is why this site exists.
There is a quote, usually credited to Robert Ingersoll, that sits at the centre of this work: we rise by lifting others. That single idea is the reason CalculatorHub exists.
Maybe you are working out your take-home pay, adding sales tax to an invoice, checking whether your retirement savings are on track, or staring down a physics formula at midnight. Whatever brought you here, you deserve a clear, accurate answer straight away, with no paywall, no sign-up and no sales funnel in between.
CalculatorHub is more than 45,900+ free calculators and plain-language guides covering tax, pay, mortgages, retirement, health, and the full breadth of science, engineering and maths. Every published figure traces to an official government, standards-body or peer-reviewed source, and every tool shows the date it was last verified. Free has always meant exactly that, and it always will.
Who is behind CalculatorHub
My name is James Graham. I am a data and analytics professional who has spent close to twenty years making practical knowledge easier to reach. I studied Human Geography and Social Anthropology alongside mathematics and statistics at the University of Auckland, a deliberate pairing: the numbers keep the tools honest, and the social science is a constant reminder that behind every calculation is a real person making a real decision. I have also worked as a quantitative analyst for various agencies and companies, and that discipline shapes how every tool here is built and checked. You can verify my background on LinkedIn.
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It started with a free course and a small grant
In 2009, in the depths of the global financial crisis, I completed Trade and Enterprise New Zealand's free "Be Your Own Boss" programme and received one of only two grants awarded to its strongest business cases. A free public programme, offered at the worst economic moment in a generation, changed the trajectory of my life. Small help, at the right moment, changes lives. I have spent the years since passing that help forward, at scale, and without a price tag.
From two hundred websites to one hub
I could not outspend the established players, so I outworked them: targeting the narrow gaps larger companies ignored and building tools that simply worked better. One calculator grew into nearly two hundred free websites reaching close to twenty million people, a portfolio that at its peak ranked among the top ten web publishers in my market. I turned down television and radio appearances along the way, because the spotlight was never the point. The person at their kitchen table late at night was.
Some tools travelled further than expected. ExamsForNursing.com gives free NCLEX practice to nursing candidates who could not afford paid preparation. A property price tool was used by hundreds of thousands of people. A salary tool exposed pay ranges across hundreds of thousands of roles, and when a prominent business figure offered to buy that data, I declined: it was built for the people using it. As the web matured, I brought everything under one roof, held to one standard. That is CalculatorHub. One site to bookmark, one place to trust.
How accuracy is maintained
Every calculator is built from scratch against primary, authoritative sources, never copied, and tested against a worked example so the formula and the published result agree. Shared rates and thresholds live in central data files, defined once and flowing through to every tool, so nothing is quietly left behind when a rate changes. Automated checks sweep the whole library for broken logic and stale figures, and every tool displays its sources and last-verified date openly.
I work with a team around the world every day to build and maintain these tools, so there is almost always someone improving or checking something, whatever the hour. If you ever find an error, tell me, and it gets fixed promptly.
The site stays free through advertising, plainly and simply. The ads fund the team and the technology, and they never come at the expense of the tools.
Part of a wider family
Calculate.co.nz is CalculatorHub's New Zealand sibling, a financial literacy platform with more than one hundred calculators covering everything from PAYE and KiwiSaver to mortgages and GST. Since early 2020 it has been the calculation partner of interest.co.nz, one of New Zealand's most trusted financial publishers, whose calculator pages carry the credit directly. Realtor.co.nz walks New Zealand property buyers, sellers and builders through the full process, first home buyers most of all. ExamsForNursing.com carries the same idea into exam preparation.
The promise
I live in a small country village west of Christchurch, in Canterbury, New Zealand, raising my young family, and much of what I build is the help I would want available to my own children if they were ever the person on the other side of the screen. Everything on this site is free, and it will stay that way. The exact answer at exactly the right moment, with no bill at the end, can change the course of someone's life. It changed mine.
We rise by lifting others.
Verify this page
Everything above is offered for checking, not just reading. Review our editorial standards, methodology and review panel, which sets out which subjects have specialist review and which have editorial review only, see every figure change in the data change history, confirm my background on LinkedIn, and see the interest.co.nz partnership credited on their own pages.
Get in touch at contact@calculatorhub.com.
CalculatorHub provides general information, not financial, tax, legal or investment advice.