We'd Love
To Hear From You

Reporting a Calculation Problem

Corrections are the most useful thing you can send us, and they are easiest to act on when the message contains enough to reproduce what you saw. A report that identifies the page and the inputs can usually be checked in minutes; one that says a result looks wrong, without them, often cannot be checked at all.

• The page — the address of the calculator or converter, since several tools answer similar questions in different ways.
• Your inputs — the exact figures you entered, including the units and any dropdown selections, because a mismatched unit is the most frequent cause of a surprising result.
• The result shown — copied as displayed rather than described, so we can tell a calculation error from a rounding or formatting one.
• What you expected, and why — the figure you were checking against and where it came from. A published rate, a lender's quote or a worked example from a textbook all tell us different things.

Where a report turns out to be right, we correct the calculation and the worked example on the page together, so the two cannot drift apart, and we check whether the same logic is shared by any related tool. Where the disagreement comes from a difference in assumptions rather than an error — a different data year, a jurisdiction we do not model, a cost we exclude — we would rather make that assumption explicit on the page than leave two defensible answers unexplained. The methodology page sets out how the tools are built and sourced.

What We Cannot Help With

Everything sent through this form reaches a real inbox and is read. Reports of a wrong number are prioritised over feature requests, and suggestions for new tools are kept and revisited — a good number of the calculators on the site began as a message from someone who could not find what they needed.