Free Online Calculators
BMI, percentage, loan EMI, compound interest, age, and unit conversion calculators — instant results with full explanations.
Featured Calculators
About Calculators
From calculating your BMI to planning a loan, free online calculators remove the guesswork from everyday maths. Multi-Toolkit provides accurate calculators for health, finance, age, and unit conversions — all with clear explanations of the formulas used.
**Health Calculators**
The BMI Calculator computes Body Mass Index from height and weight in metric or imperial units, with WHO category classifications (Underweight, Normal, Overweight, Obese) and contextual advice.
**Financial Calculators**
The Loan / EMI Calculator shows monthly payment, total interest, and an amortisation schedule for any loan. The Compound Interest Calculator projects investment growth with daily, monthly, or annual compounding — useful for FIRE (Financial Independence, Retire Early) planning.
**Everyday Calculators**
The Percentage Calculator handles seven different percentage problems: X% of Y, what percentage is X of Y, percentage increase/decrease, discount calculations, and tip calculations.
The Age Calculator shows your exact age in years, months, and days — plus days until your next birthday.
**Unit Converter**
Convert between length (metres, feet, inches, miles, km), weight (kg, pounds, stones, ounces), temperature (Celsius, Fahrenheit, Kelvin), speed (km/h, mph, m/s), and more.
How-To Guides
- 1Open the BMI Calculator and select metric or imperial units.
- 2Enter your height (in cm or feet/inches) and weight (in kg or pounds).
- 3Your BMI is calculated instantly with your WHO category.
- 4Review the healthy BMI range and contextual health information.
- 1Open the Loan / EMI Calculator.
- 2Enter loan amount, annual interest rate, and tenure in months.
- 3View your monthly EMI, total interest payable, and total payment.
- 4Scroll down to see the full amortisation schedule showing principal vs interest per month.
- 1Open the Compound Interest Calculator.
- 2Enter your principal amount, annual interest rate, compounding frequency, and investment period.
- 3View total amount, interest earned, and a growth chart.
- 4Use the additional contribution field to model regular monthly investments.
All Calculators (6)
Frequently Asked Questions
How accurate are these calculators?
All calculators use standard industry formulas. The loan calculator uses the standard EMI formula, the BMI calculator uses the WHO formula, and the compound interest calculator uses the standard A = P(1 + r/n)^(nt) formula.
What is a healthy BMI range?
According to the WHO, a BMI between 18.5 and 24.9 is considered healthy for most adults. However, BMI does not account for muscle mass, age, or ethnic variations.
How is loan EMI calculated?
EMI = [P × r × (1+r)^n] / [(1+r)^n - 1], where P = loan amount, r = monthly interest rate, n = number of months. The calculator shows this breakdown automatically.
What compounding frequency should I use?
For savings accounts, use monthly or daily. For fixed deposits, use annual or quarterly as specified by your bank. More frequent compounding increases the final amount slightly.
Can I convert between metric and imperial units?
Yes. The Unit Converter handles length, weight, temperature, speed, area, volume, and more — with real-time conversion as you type.