Choosing a calculator
Loans and borrowing
The EMI calculator and loan calculator use the standard amortization formula, where each payment covers that month's interest first and the rest reduces the principal. That is why early payments are mostly interest. The mortgage calculator applies the same maths to home loans. How mortgage amortization works walks through a full schedule.
Saving and investing
For a lump sum left to grow, use compound interest. For regular monthly contributions, use the SIP calculator or the investment calculator. The inflation calculator converts a future value into today's money. Any projection depends heavily on the return you assume: for a lump sum, 10% a year over 25 years ends up about 2.5 times higher than 6%.
Tax and pay
The GST and sales tax calculators add tax to a net price or extract it from a gross one. A common mistake when extracting is subtracting the rate from the gross price. The tax portion is actually gross × rate ÷ (100 + rate). Take-home pay and salary to hourly cover the payslip side.
Health, dates and units
BMI, TDEE and calorie calculators give population-level estimates, not diagnoses. The date tools count calendar days exactly, including leap years. The unit converters use the exact international definitions, such as 1 inch = 25.4 mm and 1 lb = 0.45359237 kg.