Calculator guides — formula & examples
Each guide explains how the matching CalcMantra calculator works: the formula, a worked INR example, and when the estimate can differ from a bank or tax filing. For “how much / should I” questions with scenario tables, use popular finance questions. To run the numbers live, open the calculator linked from any guide.
Browse hubs: loans, savings, tax, salary.
Home loan EMI explained: formula, example, and how to lower it
Learn how banks compute EMI, why early EMIs are interest-heavy, and what actually reduces total interest.
How extra EMI closes a home loan faster
Paying more than the contracted EMI reduces principal immediately. Here is why tenure shrinks and how to read the interest you still owe.
SIP calculator explained: compounding, expected returns, and corpus math
A SIP is a monthly annuity. Here is how future value is estimated and why the rate you enter matters more than the app you use.
Old vs new tax regime for Tax Year 2026-27
Budget 2026 left slab rates unchanged. Here is how rebate, standard deduction, and 80C change the comparison.
How GST is calculated in India: inclusive, exclusive, CGST, SGST, IGST
There is no single GST rate. Here is how to add tax, reverse an inclusive price (Rule 35), and split intra-state vs inter-state supply.
Gratuity formula under the Payment of Gratuity Act
Five years of service, 15 days’ wages for each year, divided by 26, capped at ₹20 lakh.