Free Online Calculators
All Your Calculations in One Place
A growing collection of free online calculators designed to help you solve everyday calculations quickly — percentage math, age & date tools, and more.
Scientific Calculator
Enter values and select Calculate to see your result.
Complete Toolkit
All Calculators
170+ tools organized by category. Find exactly what you need.
Finance 55
Math 32
Other Utilities 29
Health 26
Age & Date 7
Percentage 5
Business & Price 5
Converters 3
Planning 1
Fun 1
Popular Tools
Most used calculators
The tools people reach for every day. Start here.
Simple by Design
How it works
Go from question to answer in three steps.
Choose a calculator
Pick the tool that matches what you need.
Enter your numbers
Type in your values. Everything happens in your browser.
Get a clear result
Instant answer with formula breakdown.
Quick Answers
Frequently Asked Questions
How do I calculate a percentage of a number?
Divide the percentage by 100, then multiply by the number. For example, 20% of 200 is 0.20 × 200 = 40.
How do I find what percent one number is of another?
Divide the value by the total and multiply by 100. For example, 25 divided by 200 equals 12.5%.
Can I calculate discounts and percentage changes here?
Yes. Flux Calculator includes focused tools for percentage change, discounts, markup, margins, tips and taxes.
Are the calculators free?
Yes. The calculators are free to use and do not require an account.
About Flux Calculator & Computational Standards
Flux Calculator is an independent, comprehensive digital utility platform hosting over 170 precision-engineered calculators across finance, mathematics, health, statistics, and daily planning. Our mission is to provide lightning-fast, transparent, and mathematically rigorous calculations directly in your browser without requiring software installations or account registrations.
Mathematical Rigor and Transparency
Every tool on our platform implements established mathematical formulas and published international standards (such as ISO standards, standard financial compounding formulas, and peer-reviewed health algorithms). Unlike opaque services, every calculator page on Flux Calculator includes a dedicated formula breakdown, step-by-step worked examples, and clear methodology notes so users can verify how each result is derived.
Privacy-First Client-Side Processing
All calculations are performed locally in your web browser using client-side execution. We do not store, log, or transmit your personal financial numbers, health metrics, or private inputs to external servers. This ensures complete privacy and instantaneous response times across desktop and mobile devices.