How it's calculated
Rule of 78: rebate = total interest × n(n + 1) ÷ N(N + 1), where n is the instalments still to come and N the total. Amount to settle = the instalments still to come − the rebate.
Effective rate: amount to settle = the outstanding principal after the instalments you've paid.
Home loans inside the lock-in period add the penalty from your letter of offer; personal loans may add an early settlement fee. Your bank's redemption statement is the final figure.