To use the debt calculator simply populate the creditor fields as is applicable to yourself and click the "calculate" button. The second part of this tool allows you to tweak your repayment term, thus altering the end result accordingly.
Part 1. Commitments to your creditors
Part 2. Your result
WARNING: THINK CAREFULLY BEFORE SECURING OTHER DEBTS AGAINST YOUR HOME. YOUR HOME MAY BE REPOSSESSED
IF YOU DO NOT KEEP UP REPAYMENTS ON A MORTGAGE OR ANY OTHER DEBT SECURED ON IT.