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Free Online Calculator. Use the free online calculator for quick math, percentages, and scientific expressions right in your browser. No download or signup required.

Smart Calculator Suite

BMI, percentage, age, and date calculators — all in one place

BMI Calculator

All processing happens in your browser. No data is sent to any server.

Key Features & Benefits

BMI Calculator

Calculate your Body Mass Index with instant categorization (Underweight, Normal, Overweight, Obese). Uses the standard WHO formula and provides a visual range guide so you can understand where you fall on the spectrum.

Versatile Percentage Calculator

Three percentage modes in one tool: find X% of Y, determine what percent X is of Y, and calculate the percentage change from X to Y. Handles all common percentage calculations without switching tools.

Age Calculator with Birthday Countdown

Enter your date of birth to see your exact age in years, months, and days — plus a countdown to your next birthday. Useful for age verification, milestone planning, and just for fun.

Date Difference Calculator

Find the exact duration between any two dates in years, months, days, total days, and total weeks. Perfect for project planning, contract durations, and calculating time-based milestones.

No Server, No Signup, No Limits

Every calculator runs 100% in your browser with standard mathematical formulas. No account needed, no daily limits, and your data never leaves your device. Use them as often as you need.

Smart Calculator Suite – Frequently Asked Questions

What BMI categories does the calculator use?
The BMI calculator uses the World Health Organization (WHO) standard categories: Underweight (BMI < 18.5), Normal weight (18.5 - 24.9), Overweight (25 - 29.9), and Obese (BMI ≥ 30). These are internationally recognized thresholds for adults.
Can I use the percentage calculator for business calculations?
Absolutely! The three modes cover the most common business scenarios: calculating discounts or markups (X% of Y), determining profit margins (X is ?% of Y), and measuring growth or decline (percentage change from X to Y).
Does the age calculator account for leap years?
Yes, the age calculator uses JavaScript's native Date object, which correctly handles leap years. Your age is calculated precisely, including the extra day in February during leap years.
Are there any usage limits on the calculators?
No. All calculators in the Smart Calculator Suite run entirely in your browser with no server-side processing. There are no daily limits, no account requirements, and no cost. Use them as often as you need.