Calcaholic

Why it exists

We are calcaholics, and that is not a name we grew into. We like data and we like the calculating of data, and we will lose an entire evening settling a question nobody asked us to settle.

Compound interest and standard deviations, certainly. Also how big a boat Brody actually needed, and the odds of a given opening hand, which comes up here more than it reasonably should given one of us plays ranked. And because it would not leave us alone, the airspeed velocity of an unladen swallow.

That is the difference between a calculator built by someone who needed one and a calculator built by someone who wanted to know. The second kind explains itself, because the explaining was half the point.

What we decided

• Show the work

  A number with no reasoning attached is a number you cannot check. Every calculator explains what it did and which assumptions moved the result, and there is a page describing how the formulas get verified.

• Build for the hard cases

  Retirement, life transitions and veteran benefits are where bad math costs real money, and they are the cases most calculator sites skip because the rules are fiddly.

• Let other people embed them

  Each calculator has an embeddable version, so a site that needs one can carry it rather than rebuild it.