Calculators

Floating rate loans that adjust tenure instead of EMI on a rate rise can extend your mortgage by 7+ years — costing ₹35+ lakh in additional payments — while keeping your monthly amount unchanged. Here's how the two rate-change adjustment mechanisms work (EMI adjustment vs tenure extension), why prepayment in the first year saves 3× more than the same amount in year 15, and India's RBI rules prohibiting prepayment charges on floating-rate home loans.

A fixed deposit "guaranteeing" 5% can still leave you with less purchasing power than you started with — if inflation runs at 6%, the real return is approximately -1%, and after accounting for tax on the interest, the gap widens further. Here's the nominal-vs-real return relationship, why "nominally safe" doesn't mean "really safe," and how this gap becomes far more consequential during high-inflation periods than during the low-inflation periods many savers are used to.

Learn how inflation erodes purchasing power over time, what inflation rate to use for financial planning, and how to use a free inflation calculator to set realistic savings and retirement goals.

Savings vehicle selection depends on goal timeline — under 12 months belongs in liquid funds, 1-5 years in RDs and FDs, 5+ years in equity. Here's why the RD's natural home is the medium-term goal range, how to build emergency fund savings with an RD (then transfer maturity to a liquid account), the sinking fund approach for predictable annual expenses, and the multiple simultaneous goal commitment check that reveals when total deposits exceed sustainable surplus.

Before Grameen Bank, banks assumed poor people couldn't repay debt. Group lending with social collateral proved them wrong. Here's how the Grameen model works, why microfinance rates look high but are often justified, how M-Pesa digital credit transformed Kenya, and the debt trap problem in over-indebted markets.

Gross margin and markup describe the same profit relationship but calculate it differently — markup uses cost as the denominator, gross margin uses selling price. A business targeting "40% margin" that applies a 40% markup gets only 28.6% gross margin, systematically underpricing every product. Here's the conversion formula, why the two measures diverge dramatically at higher values (50% margin requires 100% markup), and the VAT extraction error that catches even mathematically confident people.

Salary sacrifice reduces both income tax AND National Insurance — the NI saving is the less-known part, worth 8% for basic-rate taxpayers. Here's how salary sacrifice differs from personal pension contributions (the NI is never charged rather than refunded), how employers save 13.8% employer NI on sacrificed salary and may share it, and why salary sacrifice interacts with the Child Benefit High-Income Charge threshold in ways personal contributions don't.

Banks use quarterly compounding for most RD products — here's the exact formula to verify your maturity amount independently. Includes monthly vs quarterly compounding comparison, effective annual rate conversion, and how premature withdrawal penalties are calculated.

The entire money market — Treasury bills, commercial paper, repos, and the Fed Funds Rate — uses simple interest, not because it's simpler but because the compounding period would need to be fractions of a day for instruments measured in weeks. Here's how day count conventions (Act/360, Act/365, 30/360) affect interest calculations by enough to matter in the inter-bank market, the discount rate vs investment yield distinction that makes T-bill comparisons tricky, and why the Rule of 78s front-loads interest at the expense of early repayers.

RD interest is taxable as income at your slab rate — so a 7% RD for a 30% slab taxpayer delivers roughly 4.9% post-tax. Here's how TDS on RD works (Form 15G/15H, ₹40,000 threshold), the post-tax RD comparison against PPF and SSY (both EEE exempt at similar nominal rates), why RD still makes sense for short-to-medium goals and senior citizens, and how to evaluate bank rate spreads given DICGC insurance limits.