Free Online Calculators: EMI, SIP, GST, Age, Percentage and BMI in One Place Most of us do small calculations every week. A loan instalment, a mutual fund goal, the GST on an invoice, a exact age for a form. Doing these by hand takes time, and one wrong step gives a wrong answer.
This page explains every calculator available on our site, how each one works, and how to read the result. All tools are free and need no sign-up.
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Table of Contents
- What Is an Online Calculator Tool
- Calculators Available on This Website
- EMI Calculator
- SIP Calculator
- GST Calculator
- Age Calculator
- Percentage Calculator
- BMI Calculator
- How to Use Any Calculator on This Site
- Tips for Getting Accurate Results
- Frequently Asked Questions
What Is an Online Calculator Tool
An online calculator takes a few inputs from you, applies a fixed formula, and shows the result instantly. You do not need to remember the formula or open a spreadsheet.
The tools on this site run in your browser. Whatever you enter is used only to produce the result on your screen.
Calculators Available on This Website
| Calculator | What It Finds | Inputs You Need |
|---|---|---|
| EMI Calculator | Monthly loan instalment, total interest | Loan amount, interest rate, tenure |
| SIP Calculator | Expected value of monthly investments | Monthly amount, expected return, duration |
| GST Calculator | GST amount and final price | Amount, GST rate, inclusive or exclusive |
| Age Calculator | Exact age in years, months and days | Date of birth, target date |
| Percentage Calculator | Percentage, value or change | Two numbers |
| BMI Calculator | Body Mass Index and category | Weight, height |
EMI Calculator
EMI stands for Equated Monthly Instalment. It is the fixed amount you pay every month to repay a home, car, personal or education loan.
Formula used
EMI = P x r x (1 + r)^n / ((1 + r)^n - 1)
Here P is the loan amount, r is the monthly interest rate (annual rate divided by 12 and by 100), and n is the number of months.
Worked example
| Detail | Value |
|---|---|
| Loan amount | Rs 10,00,000 |
| Annual interest rate | 9% |
| Tenure | 5 years (60 months) |
| Monthly EMI | about Rs 20,758 |
| Total payment | about Rs 12,45,500 |
| Total interest | about Rs 2,45,500 |
When it helps
- Comparing offers from two banks before you sign.
- Checking whether a longer tenure lowers the EMI enough to justify the extra interest.
- Planning a budget before applying for a loan.
SIP Calculator
A Systematic Investment Plan lets you invest a fixed amount in a mutual fund every month. The SIP calculator estimates what that habit could grow into.
Formula used
Future Value = P x [((1 + i)^n - 1) / i] x (1 + i)
Here P is the monthly investment, i is the monthly rate of return, and n is the number of months.
Worked example
| Detail | Value |
|---|---|
| Monthly SIP | Rs 5,000 |
| Expected annual return | 12% |
| Duration | 10 years |
| Total invested | Rs 6,00,000 |
| Estimated value | about Rs 11,62,000 |
| Estimated gain | about Rs 5,62,000 |
Market returns are not fixed. The result is an estimate based on the rate you enter, not a guarantee.
GST Calculator
The GST calculator adds GST to a price or removes it from a price that already includes tax. It is useful for shopkeepers, freelancers and anyone checking a bill.
| Case | Formula |
|---|---|
| Add GST | GST = Amount x Rate / 100, Final price = Amount + GST |
| Remove GST | Base price = Inclusive price x 100 / (100 + Rate) |
Worked example
| Detail | Add GST | Remove GST |
|---|---|---|
| Amount entered | Rs 20,000 | Rs 23,600 |
| GST rate | 18% | 18% |
| GST amount | Rs 3,600 | Rs 3,600 |
| Result | Rs 23,600 | Rs 20,000 |
Always confirm the correct GST rate for your product or service on the official GST portal, since rates can change.
Age Calculator
The age calculator shows your exact age in years, months and days. This is needed for exam forms, job applications, insurance and eligibility checks.
Worked example
| Detail | Value |
|---|---|
| Date of birth | 15 August 2000 |
| Calculated on | 19 October 2026 |
| Age | 26 years, 2 months, 4 days |
You can also change the target date to check your age on a past or future date, such as the last date of a form.
Percentage Calculator
This tool handles the three most common percentage questions without any manual steps.
| Question | Formula | Example |
|---|---|---|
| What is X% of Y | Y x X / 100 | 15% of 800 = 120 |
| X is what percent of Y | X / Y x 100 | 45 out of 60 = 75% |
| Percentage increase or decrease | (New - Old) / Old x 100 | 400 to 500 = 25% increase |
It is useful for marks, discounts, price changes and salary hikes.
BMI Calculator
Body Mass Index compares your weight with your height. It is a quick screening number, not a medical diagnosis.
Formula used
BMI = Weight in kg / (Height in metres x Height in metres)
Worked example
A person weighing 70 kg with a height of 1.75 m has a BMI of 22.9.
| BMI Range | Category (WHO) |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Normal weight |
| 25 to 29.9 | Overweight |
| 30 and above | Obese |
Some health bodies use lower cut-offs for Asian populations, so speak to a doctor for personal advice. BMI also does not separate muscle from fat.
How to Use Any Calculator on This Site @calculator.com.in
- Open the calculator you need from the menu or the tools list.
- Enter the values in each field. Use numbers only, without commas or symbols.
- Check that units match, for example years versus months, or kg versus pounds.
- Click the Calculate button.
- Read the result and the breakdown shown below it.
- Change any input to compare scenarios, or use Reset to start again.
Tips for Getting Accurate Results
- Enter the interest rate as a yearly figure unless the field says otherwise.
- For EMI, use the rate quoted by your lender, not a rough guess.
- For SIP, try a conservative return rate along with an optimistic one.
- For GST, select correctly whether the amount already includes tax.
- Double-check dates in the format shown in the date field.
- Treat financial results as estimates. Banks may add processing fees or round figures differently.
Frequently Asked Questions
1. Are these calculators free to use?
Yes. Every tool on this website is free, with no registration and no limit on how many times you use it.
2. Why does my bank’s EMI differ slightly from the calculator result?
Banks may round the monthly rate, add processing fees, or calculate interest from a different start date. The calculator gives the standard formula result, so a small difference is normal. Your loan agreement is the final reference.
3. Is the SIP result guaranteed?
No. Mutual fund returns depend on the market and change over time. The calculator shows what would happen if the rate you entered stayed constant for the full period, so use it for planning, not as a promise.
4. Is my data saved when I use a calculator?
The values you enter are used only to show the result on your screen. Please do not rely on a calculator for legal or tax filing without confirming the figures with a qualified professional.
