Totting up the weekly shopping whilst pushing a trolley around the local supermarket may not be too much of a challenge; but where the sums are considerably larger and the stakes so much higher - like with monthly mortgage repayments - it may be wise to opt for the assistance of a calculator.

When working out how much mortgage payments will cost each month in preparation for buying a house, remortgaging or adjusting the current payment arrangement, accurate information is vital. Otherwise, with the rising cost of living, more expensive energy and food bills and other expenses, many households might find that they don't not have enough money left over to meet mortgage repayments and could fall into arrears; so running the risk of losing their homes.

Falling house prices and rising mortgage rates mean there is a growing number of people filing for bankruptcy, or going into negative equity (where the house they own is not worth as much as the outstanding mortgage they owe), falling into arrears (where they are at least three months in arrears on their mortgage payments) and being pushed into fuel poverty, where they spend at least 10 per cent of their income solely on heating their homes.

As a result, it is wise for homeowners to put up barriers between themselves and the economic factors they cannot affect, by protecting themselves as best they can. This means, amongst other things, scrimping and saving, cutting back on luxuries, and making sure they do not take on more debt that they can afford in order to minimise monthly outgoings.

Whilst people with a mortgage rate that is variable or tracks the base rate will benefit from lower rates should the base rate fall, they will also be forever in a world of uncertainty about how much their mortgage payments will be each month because the base rate could very well go up as well as down.

Fixed rate mortgages mean that the borrower will always know how much payments will be each month for the life of the fixed rate deal. Just by entering into a mortgage calculator how much they wish to borrow, at what rate they expect to borrow it, and over what period they intend to repay it, mortgage customers can find out how much their payments would be before they take out the loan and then spend thousands of pounds on mortgage fees and other expenses only to move in and find they cannot afford it after all.

When embarking on buying a house - a process deemed to be one of the top 10 most stressful things that a person ever does - it makes sense to get all the facts and know what's to come, so there are no nasty surprises around the corner. It also means homeowners can enjoy their new home without worrying about the uncertainty of mortgage payments.