Free online calculators, done right
Done right for fast, accurate answers — mobile-friendly calculators for math, finance, health, dates and everyday life. No sign-up, no clutter.
Browse by category
Math
Percentage and other everyday math tools, calculated instantly.
Finance
Loan EMI, tax, stamp duty and investment calculators for India.
Health & Fitness
BMI, calorie and fitness calculators to track your health.
Date
Age and date-difference tools, accurate to the day.
Time
Time duration and time-sheet calculators.
Everyday
Small everyday calculators: tips, discounts and more.
Science & Weather
Physics, chemistry and weather calculators for students and pros.
Popular calculators
World Time Zone Converter (IST, EST & GMT)
Convert times between 40+ world cities with 12-hour and 24-hour formats and day-shift flags. Ideal for IST to EST, IST to GMT and calls.
Time Duration Calculator
Calculate the duration between two times or two date-times in hours, minutes and seconds — including overnight shifts. Free and instant.
Date Add Subtract Calculator
Add or subtract days, weeks, months or years to any date, including business days, and see the resulting weekday. Free, instant and precise.
Stamp Duty Calculator
Estimate stamp duty and registration charges on a property purchase, state by state. Compare male, female and joint buyer rates.
GST Calculator (India)
Add or remove GST from any amount, with CGST + SGST split for intra-state and IGST for inter-state supplies. Supports all Indian GST slabs.
Income Tax Calculator (India)
Compare your income tax under the old and new regimes for FY 2025-26 and FY 2026-27. See how much you pay in each slab and which regime saves more.
Home Loan EMI Calculator
Calculate your home loan EMI, total interest and amortization schedule. Compare tenures and see principal vs interest breakdown.
Gratuity Calculator (India)
Calculate gratuity under the Payment of Gratuity Act, 1972 with the 15/26 formula and the ₹20 lakh tax-exempt cap for Indian employees.
Percentage Calculator
Calculate percentages, percentage difference and percentage change instantly. Work out what 20% of any number is, find discounts, markups and more.
BMI Calculator
Calculate your Body Mass Index instantly and see your WHO weight category — underweight, normal, overweight or obese. Free for men and women.
Age Calculator
Find your exact age in years, months and days from your date of birth — plus total days, weeks, hours, minutes and your next birthday countdown.
Half-Life Calculator
Solve any half-life problem: remaining or initial amount, elapsed time or half-life itself, plus the decay constant and mean lifetime of exponential decay.
True Calculator works entirely in your browser. Your numbers never leave your device.
What is True Calculator?
True Calculator is a collection of free online calculators built for India and the people who use it — from percentage and date math to home loan EMI, income tax, stamp duty and health tools. Every calculator is deliberately simple: type your numbers and the answer appears instantly, with the formula and a worked example on every page so you can see exactly how the result was reached. Do it once, and it’s done right the first time.
Whether you need a home loan EMI calculator to plan a purchase, an income tax calculator to compare the old and new tax regimes, a GST calculator to price a product or a SIP calculator to plan investments, the answer is a few keystrokes away. Popular finance tools include the fixed deposit calculator, gratuity calculator, salary to in-hand calculator and retirement calculator, while the health section covers BMI, BMR, calories, body fat and ideal weight. Math, date, time, statistics, unit conversion and developer tools round out the collection — 55 calculators and counting.
The rates we use — such as bank loan rates and stamp duty figures — are regularly updated and show their “as of” date on the page. The income tax calculator compares both the old and new tax regimes for FY 2025-26 and FY 2026-27, and the stamp duty calculator covers 24 Indian states with gender concessions where they apply.
Privacy comes first. Every calculation runs on this page, in your own browser — your amounts, rates and dates never leave your device, and nothing is stored or sold. That is the True Calculator promise: accurate, transparent and private, at no cost.