Mortgage calculators

Four tools covering the questions that come up before, during and after a home loan: what the payment is, whether to overpay, whether to refinance, and what you can actually afford.

4 calculators

Mortgage Payment CalculatorWork out the monthly principal and interest on a fixed-rate mortgage, the total interest over the full term, and how much of your first payment reduces the balance. Formula shown.Extra Payment CalculatorSee how many payments a recurring extra principal payment removes and how much interest it saves, across a ladder from $50 to $1,000 a month, on your own loan figures.Refinance Break-Even CalculatorFind the month at which a lower rate has recovered the closing costs, see your cumulative position year by year, and test how small a rate cut stops being worth it.How Much House Can I Afford?Work backwards from income and existing debt to a maximum purchase price, with the result shown under four different debt-to-income bands so you can see whose judgement sets the ceiling.

About this cluster

The rate anchor across this cluster is the Freddie Mac Primary Mortgage Market Survey, the weekly national average for conventional conforming purchase loans. It is a national average reported on an application basis, not a quote for any individual borrower, and every page that uses it says so.

How the figures are checked

Each calculator in this cluster states its formula, ships with worked examples that were checked against a known answer by an independent second implementation, and lists the primary source and retrieval date behind every external figure. The full method is described on the methodology page.