CalculatorWorld (calculatorworld.in) is an independent website, based in India, that publishes free online calculators and plain-English guides for money, health, education, dates, unit conversions and developer tasks. We started in 2026 with one goal: build a calculator site that people can trust. That means each tool gives a correct answer and explains how it got there.
What we do
We currently offer 41 calculators and converters across seven categories. Every tool has its own page with:
- a working calculator that runs in your browser,
- the formula or official rule behind it,
- worked examples using realistic Indian figures,
- reference tables and answers to common questions, and
- a clear note of what the tool does not cover.
Our audience is mainly in India, so we design for Indian rules and conventions: lakhs and crores, income-tax regimes, GST, PF, RBI loan rules, university grading and the 75% attendance requirement. Most tools are just as useful anywhere.
Editorial policy
Sources
Calculators are built only from published formulas and primary sources, including:
- Tax and finance: Union Budget documents, the Income Tax Department (incometax.gov.in), CBIC GST notifications, RBI circulars and master directions, AMFI and SEBI material.
- Health: World Health Organization classifications, peer-reviewed equations (such as Mifflin-St Jeor, 1990), Indian consensus guidelines for Asian-Indian BMI cut-offs, and EFSA and ICMR-NIN reference values.
- Education: UGC grading guidelines, board and university ordinances.
- Units and time: SI and BIPM definitions, the IANA time-zone database and ISO 8601.
Where we cite figures on a page, we name the source on that page.
Testing
Before a calculator is published, we check its output against several hand-worked examples and independent references, including edge cases: leap-year birthdays, month-end dates, zero interest rates, income just above a rebate limit. The worked examples on each page are calculated independently and cross-checked against the tool.
Reviews and updates
Every page shows a “last updated” date. We review finance and tax tools after each Union Budget and whenever the GST Council, CBDT or RBI changes a relevant rule, and we review all other tools at least once a year. When a rule changes, we update the calculator and its explanation together.
Corrections
If you find an error, please tell us. We check every report. Confirmed errors are fixed promptly and the page’s update date is changed.
Independence and advertising
CalculatorWorld is free to use and is supported by display advertising (Google AdSense). Advertisers have no influence over our calculators or content. We do not accept payment to recommend financial products, and the site contains no paid or sponsored rankings.
Our principles
- Accuracy over volume. We would rather publish 41 calculators we have tested properly than hundreds of unchecked ones.
- Privacy first. Your inputs stay on your device. Calculators don’t send what you type to our server.
- Explain, don’t just compute. Showing the formula helps you spot a wrong input and understand the result.
- Honest limits. Calculators give estimates. For important financial, tax, legal or medical decisions, we encourage you to talk to a qualified professional, and our pages say so.
- Fast and accessible. Lightweight pages that work on low-end phones and slow connections, with readable text and keyboard-friendly controls.
Contact
Questions, corrections or ideas for a new calculator: email hello@calculatorworld.in or visit our contact page.