Calculators

A calculator is only as honest as the assumptions buried in it, and most of the ones you will find for Indian products quietly get those assumptions wrong. Deposit calculators that compound annually understate an FD that actually compounds quarterly. Loan calculators built on a flat interest rate flatter a product that is really charged on a reducing balance. Retirement calculators return a corpus and stop, as though the corpus were the thing you wanted rather than the income it eventually buys.

These are built the other way round. The financial maths lives in one tested module that runs both when the page is built and when you change a number in the browser, so the figure on screen cannot drift away from the method described underneath it. Every calculator states its compounding convention, its rounding, and what it deliberately does not model — an EMI figure that ignores the processing fee is not wrong, but you should know it is the loan without the fee rather than the loan.

Two habits make these more useful than a single answer. First, run the pessimistic case as well as the expected one: a SIP projection at a lower assumed return tells you more about whether a goal is safe than the headline number does. Second, compare after tax wherever tax differs between the options — the deposit and small savings calculators here are frequently the fastest way to see that a lower advertised rate wins once its treatment is accounted for.