💰 Money & Finance guides

How to use these money guides

Most personal-finance questions come down to a handful of formulas: interest on a balance, a fixed monthly payment on a loan, a percentage added to or taken off a price, and money spread over time. Once you understand those few ideas, you can check almost any offer, payslip or savings plan yourself. Each guide below explains one idea in simple steps, shows a worked example with real numbers, and then links to the free calculator that does the arithmetic for you.

The core ideas, in the order we suggest

1. Percentages. Tax, discounts, tips, margins and interest rates are all percentages. If percentages feel shaky, start with the percentage guides in Math & Dates.
2. Compound interest. Interest earned on earlier interest is what makes savings grow and debt expensive. Learn how monthly compounding changes the result.
3. Loan payments (EMI and mortgages). A fixed payment that slowly shifts from mostly interest to mostly principal. Understanding amortization helps you compare loans by total cost, not only by the monthly figure.
4. Income and budgets. Converting hourly pay to a salary and setting a monthly saving target turn vague goals into numbers you can plan around.
5. Business basics. Profit margin and markup look similar but answer different questions. Mixing them up is one of the most common pricing mistakes.

A note on accuracy

Our calculators and guides are for education and planning. Real loans include fees, insurance and rules that differ by country and lender, and tax rates change. Use the results to understand your options, then confirm exact figures with your lender, employer or a qualified adviser before you sign anything.