Loan guides

Plain-English explainers on how borrowing actually costs money. Each guide works through real numbers rather than rules of thumb, because the arithmetic of a loan is where the money is. Everything below was produced by our loan calculator and independently recomputed before publication.

Where to start

The twenty-three guides are not a course to be read in order — they answer twenty-three different questions. Find the one closest to your situation:

How these guides are written

Every figure in these guides comes from the same calculator code that runs on this site, and each one is then recomputed with a second, independent implementation before publication. Where the two disagreed, the guide was rewritten rather than averaged — which is why the worked examples carry exact totals like $1,896.20 and $382,633 instead of round numbers. You can reproduce any of them yourself in the loan calculator.

Two things you will deliberately not find here. First, no “current average rate”: a rate printed today is wrong next month, so each example fixes a rate explicitly as an illustration and shows what follows from it. Second, no advice about your particular loan — the guides explain how the arithmetic works and which numbers to collect, then leave the decision to you.

Some rules genuinely do depend on where you live or on the terms of your own contract: state sales tax treatment, the threshold at which mortgage insurance can be cancelled, income-driven repayment formulas. On those points a guide says so and points you to the document that governs, rather than presenting a national generalisation as though it were a fact. Every guide is reviewed by David Chen and lists the date it was last checked.

Reviewed by David Chen · Last reviewed October 11, 2026. These guides are educational and are not financial advice. Spot an error? Tell us — see also our disclaimer.