Free tool

Smart Calculators

Everyday math should not require a spreadsheet or an app install. Our Smart Calculators bundle five of the most-used calculators — loan repayment, percentage, age, Body Mass Index (BMI), and unit conversion — into one fast, private tool that runs entirely inside your browser. Nothing you type is ever uploaded to a server.

Whether you are planning a car loan, checking a discount at the store, working out your exact age in days, tracking your health, or converting kilometres to miles, you get an accurate answer the instant you type. No sign-up, no ads interrupting the math, no waiting.

Smart Calculators

A suite of everyday calculators: loans, percentages, age, BMI, and unit conversion — all running instantly in your browser.

Loan Amount

Annual Rate %

Term (years)

Monthly Payment

Total Interest

Total Paid

100% local — no data ever leaves your browser.

How to use the calculators

1 Pick the calculator you need from the tabs: Loan, Percent, Age, BMI, or Units.
2 Type your values into the input fields — results update live as you type.
3 For the loan calculator, enter the amount, annual interest rate, and term in years.
4 For BMI, switch between metric (cm/kg) and imperial (in/lb) with one click.
5 Copy or note the result — nothing is stored, so refreshing clears everything.

Why use our calculators

Instant results

Every calculation runs locally, so answers appear the moment you type — no page reloads.

100% private

Your numbers never leave your device. There is no server, no logging, no tracking of what you calculate.

Works everywhere

Runs on any modern phone, tablet, or desktop browser with no install required.

Common use cases

Estimating the monthly payment and total interest on a car, home, or personal loan before you borrow.
Calculating discounts, tips, tax, or markups as a percentage of any amount.
Finding your exact age in years, months, and days — useful for forms, visas, and milestones.
Checking your BMI to understand where you sit on the healthy-weight scale.
Converting between metric and imperial units for cooking, travel, DIY, and study.

Frequently asked questions

Is the loan calculator accurate for real mortgages?

It uses the standard amortization formula that banks use for fixed-rate loans, so the monthly payment and total interest are accurate. Real loans may add fees or insurance that this tool does not include.

Are my numbers sent anywhere?

No. Every calculation happens in your browser using JavaScript. Nothing is uploaded, saved, or shared.

Does the BMI calculator support pounds and inches?

Yes. You can switch between metric (centimetres and kilograms) and imperial (inches and pounds) with a single tap.

Do I need to create an account?

No account and no sign-up are required. The calculators are completely free to use.

Related tools

Password Generator

Image Converter

PDF Merger & Creator