Calculator guides
Plain-language explanations of the formulas behind our most-used calculators, with worked examples you can check yourself.
GuideHow EMI Is CalculatedLearn the EMI formula step by step with a worked loan example, see how rate and tenure change total interest, and how prepayment cuts cost.GuideCompound Interest ExplainedUnderstand compound interest with the formula, worked examples at different compounding frequencies and the Rule of 72 for doubling time.GuideSIP vs LumpsumSee how the SIP future-value formula works, compare SIP and lumpsum on equal terms with worked numbers, and learn what calculators cannot predict.GuideBMI ExplainedHow BMI is calculated, what the WHO categories mean, why cut-offs can differ between populations, and when BMI is a poor measure of health.GuideHow to Calculate PercentagesLearn the percentage formulas for percent of a number, percentage change, discounts and tips, with worked examples and common mistakes to avoid.GuideHow to Convert Currency and Avoid Hidden FeesUnderstand mid-market versus bank exchange rates, how spreads and fees work, how cross rates are calculated and simple steps to keep more of your money.