Every calculator below deals with debt already taken on, rather than borrowing you are about to do. The two figures that matter are rarely the same: what a debt costs per month, and what it costs in total once every payment is added up. A monthly figure that looks manageable can still be dragging a repayment date years further out than it needs to be, and a lower rate on paper does not always beat a shorter term.
Calculators in this section
Credit cards get separate treatment from instalment loans because they compound differently — interest applies daily to whatever balance is still outstanding, rather than being fixed at the start against a schedule that steadily reduces it. That difference is why a card balance carried for years can cost far more than a personal loan of the same size, even at a similar headline rate.
Where more than one debt is in play, the ordering question — clear the smallest balance first or the most expensive rate first — changes the total interest paid without changing anything about what is owed. Mortgages sit in their own section because a mortgage is secured against a specific property and priced accordingly; the debt maths here applies to everything else.