Who builds this site
CodingMarble Calculator is made by CodingMarble, a small independent team of web developers based in India. There is no company floor and no marketing department behind it – the same few people choose the formulas, write the code, write the explanation under each tool and answer the email when something looks wrong.
We started building calculators because we kept needing them ourselves and kept landing on pages that asked for a sign-up, buried the answer under a wall of pop-ups, or printed a number without saying how it got there.
Alongside this site we run a handful of other free tools on the same domain: LovePDF for PDF files, LoveImage for photos, a QR code generator, a biodata and resume maker, a typing test, learning games for young children, yoga and workout guides, and school lessons for Class 8 to 12.
What this site covers
There are currently 82 calculators here, grouped into five areas:
- Money and loans – EMI, home and car loans, SIP, FD, RD, PPF, EPF, NPS, Sukanya Samriddhi, compound interest, CAGR and retirement.
- Tax and salary – income tax, GST, in-hand salary, HRA and gratuity.
- Health and fitness – BMI, BMR, calories, TDEE, body fat, macros, pregnancy due date and ovulation.
- Maths and school – percentages, fractions, statistics, geometry, a scientific calculator, GPA and CGPA.
- Everyday and converters – age, dates, hours, fuel cost, electricity bills, units, currency and time zones.
Every page carries the formula it uses, one worked example with real numbers, and answers to the questions people actually ask about that calculation. If you want the full method – where the formulas come from, how results are tested, what we do when the government changes a rate – it is written out on how we check every calculator.
What we hold to
- Free, with no account. Nothing is paywalled, there is no sign-up, no trial and no "unlock the full result".
- Nothing is stored. Your salary, loan amount, weight or last period date never leaves your device, because the maths runs inside your browser. We do not have a database of your inputs to lose or sell. The details are in our privacy policy.
- The formula is on the page. You can check our arithmetic with a pen, which is the only honest way to earn trust with numbers.
- It works on a cheap phone. Pages are plain HTML and small enough to load on a slow connection on an entry-level Android handset. That is what most of our visitors use.
- Estimates, clearly labelled. We say what a result is good for and where it stops. A lender, employer, tax officer or doctor has the final figure, not us.
How the site is paid for
Advertising covers the hosting bill and the time spent building the tools. That is the whole business model: no subscriptions, no lead selling, no sponsored calculators that quietly favour one bank or fund.
Ads are kept out of the way on purpose. There are none inside the calculator panel, none over the input fields or the result, and none that float, follow you down the page or cover the screen. Each ad sits in a reserved space after the result, inside the article or after the FAQs, so the page does not jump while you are typing a number. If an ad ever gets in the way of using a tool, that is a bug – tell us.
Reaching us
Email support@codingmarble.com or use the contact page. A wrong result, a confusing label, an out-of-date rate or a calculator you wish existed – all of it is useful. Corrections get priority, and we will tell you what we changed. Our terms of use set out the rest.