United Kingdom
UK mortgage calculators
Built around how UK repayment mortgages work: fixed deals that end and revert to a variable rate, overpayment allowances with early repayment charges above them, and the choice of a shorter term or a lower payment.
Calculators
Mortgage overpayment calculator
Monthly or lump-sum overpayments from today's balance: your new mortgage-free date, the interest saved, and whether you stay within your 10% allowance or pay an early repayment charge.
Fixed rate ending calculator
What your monthly payment becomes when your fixed deal ends and you move to the standard variable rate or a new deal, and what overpaying before then does to it.
Guides
What the rules let you do, what each choice costs, and the order to do things in.
Should you overpay your mortgage or save?
The return overpaying earns, what a savings account or ISA has to beat after tax, and the order to do things in.
The 10% overpayment rule and early repayment charges
How the annual allowance works, which balance it is taken from, when the ERC bites, and how to overpay more without paying it.
What happens when your fixed rate ends
The standard variable rate, product transfers and remortgaging, when you can lock in a new deal, and how to soften a payment jump.
How these calculators treat a UK mortgage
Every calculation starts from the balance you owe today, not the amount you borrowed, so it works for a mortgage you are years into. Interest is charged monthly on the balance and rounded to the penny; most UK lenders calculate it daily, which lands within a few pounds. When a deal ends, the payment is recalculated over the term left at the new rate, as lenders do. Overpayments are checked against your deal's annual allowance, and any early repayment charge on the excess is shown next to the interest saved. Nothing you type is sent to a server. The full method is on How we calculate, and the US calculators cover American mortgages.