What it actually costs each month.

It is an accurate capital-and-interest payment for the figures entered, calculated the same way a lender calculates it. What it is not is a quote: it assumes one rate for the whole term, excludes every fee, and takes no view on whether a lender would advance that amount to you. Treat it as the shape of the answer rather than the answer.

Whatever you are being quoted, if you have a quote. If you do not, run it at a rate somewhat above what you expect — that is broadly what a lender's affordability stress test does, and if the payment still looks comfortable at that level then the real one certainly will.

Most lenders want at least five per cent of the price, and the products at that level are limited. Ten per cent opens up materially more, with further improvements at fifteen and twenty-five. Because pricing works in bands rather than smoothly, it is always worth checking where the next threshold sits before concluding you have saved enough.

The loan as a percentage of the property's value — the mirror image of your deposit. It is the figure that most determines which products are available to you, because lenders price in bands. The value used is the lender's own valuation, not the price you agreed, so a low valuation raises your LTV even though nothing else has changed.

A shorter term costs more each month and dramatically less in total. The right answer is the shortest term whose payment you could still meet in a bad year, not the shortest one you could meet in a good one — and a longer term with regular overpayments achieves much the same result while keeping the flexibility to stop.

No. This calculates a capital-and-interest payment, where the balance reaches zero at the end of the term. An interest-only payment is simply the interest on the balance, and the balance itself is still outstanding at the end — which is a different question, and one that needs a repayment plan rather than a calculator.