Free Online Calculators

Quick, accurate calculators for students, health and everyday life. Each one explains its formula with a worked example.

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Student calculators

🎓GPA CalculatorWork out your semester and cumulative GPA on the 4.0 scale, weighted or unweighted.
📊CGPA CalculatorCombine semester SGPAs into your CGPA and convert CGPA to percentage.

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Health

⚖️BMI CalculatorCheck your body mass index in kg/cm or lb/ft and see your healthy weight range.

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Astrology & fun

✨Zodiac Sign CalculatorFind your star sign and Chinese zodiac animal from your birthday.
💞Zodiac CompatibilitySee how two star signs match in love and friendship.

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Dates

🎂Age CalculatorGet your exact age in years, months and days, plus your next birthday.

📘 Guides

What Is a Good GPA?

GPA ranges for high school, college, grad school and jobs, and how to raise yours.

How to Calculate GPA

The formula, the 4.0 scale and worked examples for semester, cumulative and weighted GPA.

Weighted vs Unweighted GPA

How honors and AP classes change your GPA, with a worked example.

Healthy Weight Chart by Height

Healthy weight ranges for every adult height, in pounds and kilograms.

Chinese Zodiac Years Chart

The animal and element for every year from 1924 to 2031.

Zodiac Compatibility Chart

Love scores for every pair of the 12 star signs.

YouTube Thumbnail Size Guide

The right size, format and file limit, plus design tips.

What Is YouTube RPM?

How much YouTube pays per 1,000 views, and how to earn more.

By Shah Rukh, software developer · Last updated: September 27, 2026

About these calculators

The GPA calculator and CGPA calculator use the standard credit-weighted methods and point out where universities differ. The BMI calculator follows World Health Organization categories. The age calculator handles leap years correctly, and the zodiac tools are just for fun.