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Calculators

Unit, date, finance and health calculators that show the assumption behind the number.

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All Calculators

Grouped by what you want to get done. Star a tool to find it again on the homepage.

Money · Loan EMIs, GST and percentages.

3

EMI Calculator

Calculate monthly EMI for loans with breakdown of principal and interest

GST Calculator

Calculate GST inclusive/exclusive amounts and breakdown by tax slab

Units and time · Measurement units, time zones and Unix timestamps.

3

Unit Converter

Convert between length, weight, temperature, area, volume, speed and more

Everyday maths · Exact age from a birth date, and BMI.

2

Age Calculator

Calculate exact age in years, months, days and hours from a birthdate

BMI Calculator

Calculate Body Mass Index with metric and imperial unit support

Numbers and words · Write any amount in words, in lakh and crore or in millions.

1

Number to Words

Write any amount in words, in lakh and crore or millions, with rupees and paise

Related tools

Often used alongside these, from other categories.

About these Calculators

A calculator is only as honest as the assumptions it hides. Unit conversion is exact because the factors are defined; currency conversion is not, because there is no fixed rate between two currencies, only a rate at a moment and a spread that depends on who is doing the converting. Loan and tax calculators sit in between: the arithmetic is exact, but the result depends entirely on inputs that are rarely as fixed as they look.

Choosing between these Calculators

Exact conversions and estimated ones are different things

An inch is exactly 25.4 millimetres by definition, so that conversion has no error. A BMI figure, an EMI schedule or a tax estimate is a model with inputs, and changing one input meaningfully changes the answer. Treat the first kind as fact and the second kind as a starting point.

Dates are harder than they look

Age, duration and deadline calculations run into leap years, month lengths that vary, and time zones where "the same day" starts at different moments. When a date calculation matters legally or financially, check which convention the other party is using before trusting any tool's answer.

Percentages compound differently than people expect

A 20% fall followed by a 20% rise does not return to the starting value, and an annual rate applied monthly is not one twelfth of it. Where a calculator here deals in rates, the compounding basis is stated, because it is the input people most often get wrong.

Questions people ask

Are these calculators accurate enough to rely on?
For unit conversion, yes: the factors are the internationally defined ones and the arithmetic is done in double precision. For financial and health calculators, the arithmetic is exact but the result is a model: an EMI figure ignores fees your lender may charge, and BMI is a population-level statistic that says little about an individual.
Why is there no live currency conversion?
Because an honest currency converter needs a live rate from a source that updates continuously, which is a server-side dependency this site deliberately does not have. A converter showing a rate cached days ago is worse than no converter, since it looks authoritative and is wrong.
Do these work offline?
Yes. Everything here is arithmetic running in the page, so once it has loaded, no calculator on this list needs the network again.

Guides on this topic

Unit conversion is not one multiplicationTwice the temperature in Celsius is not twice the temperature. Half the conversions people treat as multiplication are not multiplication.EMI, GST and percentages: the formulas the calculators are runningA 20% rise followed by a 20% fall does not get you back to where you started. That is not a rounding error, and the same confusion makes tax and loan figures wrong.Cron expressions: reading the five fields without guessingA schedule that should fire monthly fires every Monday as well. The two day fields are combined with OR, not AND.Unix timestamps, UTC and the off-by-one-hour bugYour report is right eleven months of the year and wrong for one week in spring. That is daylight saving, and the fix is upstream of the report.