Rates and costs — mortgage guides

Fixed against variable, what APR includes that the headline rate does not, and how interest is calculated month by month on a falling balance.

Mortgage basics Rates and costs Affordability and deposit Mortgage types Refinancing and overpaying

3 guides

A falling stack of blocks — the balance the interest is charged on

How Mortgage Interest Is Calculated, Month by Month

Interest is charged on what you still owe, not on what you borrowed. That one sentence explains amortisation, overpayment savings and daily interest.

Rates and costs 8 min read

The headline figure is one line on a long invoice

APR and Fees: Why the Cheapest Rate Is Often the Expensive Deal

A large arrangement fee can turn the best headline rate into the worst offer. Here is how APR works, what it misses, and how to compare properly.

Rates and costs 9 min read

Two paths from the same door — certainty on one side, movement on the other

Fixed or Variable? The Decision Is About Your Budget, Not the Market

Fixed buys certainty and costs a little more; variable starts lower and moves. The honest test is what a three-point rise would do to you.

Rates and costs 9 min read

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Last updated 2026-08-06 by mortgagecalculator.siten.co · About us

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Every guide is researched and written by our editorial team, not rewritten from a lender’s marketing page.

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The arithmetic is shown

Where a figure comes from a formula we print the formula, so you can check it rather than trust it.

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