Make the decisions
that actually matter.

Answer the yes/no questions in "Which calculators fit your life?" at the top of this page. Or enter your age, net wealth and annual income next to it: the financial potential map then ranks every calculator by its rough 10-year impact for someone like you. You can also search the full list or browse it by category.

No. Every calculation runs in your browser. There is no account and no database, and your inputs are never sent to us. The web server keeps an access log for security and operation. It records a shortened IP address, the time, the page path and the response status, but never the part of a share link that holds your numbers. Settings and inputs only outlast your visit if you switch that on, and then they stay on your own device.

Yes. Everything is in today's money. The global Market Return (in Settings) and every rate field on the site is a real rate, meaning growth or interest above inflation, and each of those fields is labelled "real". To convert a rate you know in ordinary terms, subtract inflation: at 2% inflation, a 3.5% mortgage rate is about 1.5% real and a 3% pay rise is about 1% real. Amounts you type in (rent, salaries, costs) are today's amounts.

Yes. The Share button puts every input of the calculator into the link, so whoever opens it sees your exact numbers. Anyone who has the link can read those numbers, so share it the way you would share the figures themselves. The server log keeps only the page path, not the numbers.

That depends on the calculator, so there is no single list. Each calculator has its own "What this ignores" card below its explanation. It names what that model leaves out and whether this makes the result look better or worse than reality.

An average hides the spread, and for a big decision the spread matters: how bad could it get, and how often? Calculators that depend on market returns show the range from P10 to P90 (a bad case and a good case) around the median, as a shaded band or as a histogram. Most of them compute that range exactly from the maths of the model. Four (Explore vs Exploit, Many Small Bets, Compound Growth and Portfolio Mix) run their own simulation instead, because there the simulation is the point.

Investment returns compound: each year's return multiplies onto the last instead of adding to it. The growth rate a typical portfolio actually achieves over time is the geometric mean, which is also the median outcome when returns are lognormal. The arithmetic average is always higher whenever returns vary, because a few very lucky paths pull it up. Most investors never get those paths, so planning with the arithmetic average overstates what you are likely to end up with.

Returns compound by multiplication, and a price cannot fall below zero. A normal (bell-curve) distribution of returns would allow losses of more than 100%, which is impossible. A lognormal model multiplies your wealth by a random growth factor each period, so it can never drop below zero. It is a modelling choice with known limits: real markets crash more often than a lognormal model predicts.

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