Calculators Learning Hub
Understand the math behind every calculation.
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View All GuidesHow EMI Works — Principal, Interest & Tenure Explained
EMI stands for Equated Monthly Instalment. Learn how lenders calculate your monthly payment, how tenure and interest rate affect it, and how to use this knowledge to borrow smarter.
5 min read
What is GST? CGST, SGST and IGST Explained
GST replaced 17 indirect taxes in India with one unified tax. Learn how CGST, SGST, and IGST work, what the 5 tax slabs are, and how to calculate GST on any invoice.
5 min read
How to Calculate a Percentage — 3 Methods with Examples
Percentages come up everywhere — discounts, tax, exam scores, growth rates. Here are the three core calculations every person needs to know, with worked examples for each.
5 min read
How SIP Works — Rupee Cost Averaging & the Power of Compounding
A Systematic Investment Plan (SIP) lets you invest a fixed amount every month into a mutual fund. Learn how rupee cost averaging reduces risk, how compounding grows your wealth, and how to pick the right SIP amount.
5 min read
All Calculators Guides
26 guidesHow to Use a Scientific Calculator: A Complete Guide
Learn what a scientific calculator does, how trig and log functions work, the difference between DEG and RAD, operator precedence, and common mistakes to avoid.
25 Jun 2026
5 min read
Tip Calculator Guide: How to Tip and Split a Bill Fairly
A practical guide to calculating tips and splitting restaurant bills — tip percentages by country, how the per-person maths works, service charges, and group-dining etiquette.
25 Jun 2026
5 min read
How to Save Income Tax in India: 80C, 80D, HRA and Beyond
A practical guide to the deductions that cut your tax under the old regime — 80C, 80D, HRA, NPS, and home-loan interest — and when they beat the new regime.
24 Jun 2026
5 min read
Ideal Body Weight Formulas: Devine, Robinson, Miller, Hamwi
What the classic ideal body weight formulas actually measure, how Devine, Robinson, Miller, and Hamwi differ, and why a healthy weight is a range, not a single number.
24 Jun 2026
5 min read
New vs Old Tax Regime (FY 2025-26): Which Should You Pick?
A clear walkthrough of India's new and old income tax regimes for FY 2025-26 — the slabs, the standard deduction, the Section 87A rebate, and how to decide between them.
24 Jun 2026
5 min read
Lumpsum vs SIP: How a One-Time Investment Grows
Understand how a lumpsum investment compounds, what maturity value and effective CAGR mean, how compounding frequency changes the result, and when a lumpsum beats a SIP.
24 Jun 2026
5 min read
How a Mortgage Works: Payments, Interest & LTV
Understand how a home-loan payment is built from principal, interest, tax, and insurance, why early payments are mostly interest, and how down payment and term change the cost.
24 Jun 2026
5 min read
Mortgage Prepayment: How Extra Payments Save Interest
Learn how prepaying a home loan saves interest, the difference between reducing tenure and reducing EMI, when to prepay versus invest, and how to model the savings.
24 Jun 2026
5 min read
BMR, TDEE and Calorie Targets, Explained
What BMR and TDEE mean, how activity multipliers work, how to set a safe calorie deficit or surplus, and the role of macros — a clear, practical guide.
23 Jun 2026
5 min read
LTCG vs STCG in India: How Capital Gains Tax Works
A plain-English guide to capital gains tax in India after Budget 2024 — holding periods, the 12.5% LTCG rate, the ₹1.25 lakh exemption, and how to estimate your bill.
23 Jun 2026
5 min read
Body Fat % vs BMI: Why One Tape Measure Beats Your Smart Scale
BMI can't tell muscle from fat. Body-fat % can. Here's the math behind the US Navy method, why a $5 tape beats most bioelectrical-impedance scales, and where each metric breaks down.
16 May 2026
5 min read
BMR vs TDEE, Explained: How the Three Formulas Compare
BMR is the floor. TDEE is the real number you eat against. Here's how Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle differ, when each is right, and why your smart-scale BMR disagrees with all of them.
16 May 2026
5 min read
PPF, Explained: How the 7.1% Tax-Free Engine Actually Works
PPF is the only Indian retail product that's Govt-backed, §80C-eligible, and entirely tax-free at maturity. Here's how the math compounds, why timing matters, and the case for max-funding ₹1.5L every April.
16 May 2026
5 min read
UK Alcohol Units, Explained: The Math Behind '14 a Week'
One UK unit = 10 ml of pure ethanol. Here's where that number comes from, why a pint of normal lager is 2.3 units (not 2), how the 14-unit weekly guideline was set, and what the math doesn't tell you.
16 May 2026
5 min read
Verhoeff Algorithm Explained: How Aadhaar Detects Typos
The 12th digit of every Aadhaar number is a Verhoeff check digit. Learn how this 1969 algorithm catches almost every single-digit typo and most digit swaps — the same math you can verify yourself in our Aadhaar Format Validator.
16 May 2026
5 min read
How to Use FD Calculator — Complete Guide
Learn how to calculate Fixed Deposit maturity amount and interest earned using the free FD Calculator on Tools.Town — all compounding frequencies, TDS, senior citizen rates.
7 May 2026
5 min read
How to Use PPF Calculator — Complete Guide
Learn how to calculate PPF maturity amount and year-by-year growth using the free PPF Calculator on Tools.Town — for all deposit scenarios and the current interest rate.
7 May 2026
5 min read
How to Use Loan Calculator — Complete Guide
Learn how to calculate loan EMI, total interest, and amortization schedule using the free Loan Calculator on Tools.Town — for home loans, car loans, and personal loans.
7 May 2026
5 min read
How to Use Salary Calculator — Complete Guide
Learn how to calculate take-home salary from CTC using the free Salary Calculator on Tools.Town — covers Basic, HRA, PF, income tax (old vs new regime), and in-hand salary.
7 May 2026
5 min read
BMI Chart Explained — What Your Number Really Means
Your BMI is a number between roughly 10 and 50. Here's what each range means, how BMI is calculated, where it falls short, and what to do with the result.
1 May 2026
5 min read
Compound Interest Explained — How Your Money Grows on Itself
Compound interest is interest earned on both your principal and your previously earned interest. Understand the formula, the difference from simple interest, and why starting early makes such a dramatic difference.
1 May 2026
4 min read
How to Calculate a Discount — Percentage Off, Final Price & Savings
Discounts are everywhere — sale tags, coupon codes, trade margins. Learn the three discount formulas you actually need: percentage off, final price after discount, and what discount percentage a price drop represents.
1 May 2026
4 min read
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