How to contact us to report a calculator error
The most useful report names the page, the values you entered in every field and the figure you expected, with a source if you have one. A missing input is the usual reason a result cannot be reproduced. Screenshots are not needed, since the arithmetic in every calculator is deterministic: the same inputs give the same output each time. If the page shows a worked example that disagrees with the live calculator, mention both.
Corrections are checked against the calculator’s formula and cited source. When a report is confirmed, the calculator or the page is fixed and the change is described on the corrections page, so the record of what changed stays public. Reports that turn out to be a difference in assumptions, such as a rate entered as a percentage instead of a decimal, are answered with an explanation of the input that caused the gap.
Privacy questions and requests
Calculator inputs are processed in your browser. The only information the site receives is what you type into this form, so a privacy question needs no account details and no calculation history. Say which page you were on and what you want to know: what is stored, for how long, or how a cookie or measurement tool behaves. The privacy page describes the current practice, and a question that page does not answer is a useful sign that it needs a clearer sentence.
Suggesting a calculator or a definition
Several calculators exist because a reader described the decision they were stuck on. A good suggestion says what you are trying to decide, which numbers you have in hand and what you would compare. Definitions can be requested the same way: name the term, the page where it confused you and the source you read. Suggestions are weighed against what the library already covers, so mention the closest existing calculator and what it lacks.
What this site cannot answer
The calculators are educational tools and cannot give personal financial, tax, legal or medical advice. A question about which choice is right for you, whether you owe a particular tax or how a rule applies to your case belongs with a qualified professional who can see your documents. Messages that ask for individual advice can only be pointed to the general explanation on the relevant page.