Percentage Calculator - Increase, Decrease, Discount and Difference Free

Introduction: What Is the Percentage Calculator?

The Percentage Calculator by Trencada is a free online tool that solves common percentage problems in seconds. Whether you need to find what percentage one number is of another, calculate X% of a value, measure percentage change, or increase or decrease a number by a percentage, you get an instant, accurate answer — no formulas to memorize and no software to install. Every calculation runs 100% in your browser, so your numbers never leave your device. If you also plan loans, savings, or gratuities, try our Mortgage Calculator, Retirement Calculator, and Tip Calculator for more everyday math.

How to Use the Percentage Calculator on Trencada.com

Using the Percentage Calculator is simple:

1. Enter your numbers in the "Value A" and "Value B" fields. The field labels update automatically when you change the calculation type.
2. Choose one of the five calculation types: "A is what % of B?", "What is X% of B?", "Percentage change from A to B", "Increase A by B%", or "Decrease A by B%".
3. Set your output options: round results to 2 decimal places, show the calculation formula, or show all calculation types as a summary.
4. Click the "Calculate" button to see your result instantly.
5. Use "Copy Result" to copy the answer to your clipboard, or "Start Over" to reset the form and run a new calculation.

Key Features

Five Calculation Types in One Tool

Switch between what-percent, percent-of, percentage change, percentage increase, and percentage decrease without reloading or opening another page.

Smart Input Labels

The labels between the input fields update automatically — "is what % of", "% of", "→", "+", or "−" — so you always know exactly what the tool is computing.

See the Formula Behind Every Result

Enable "Show calculation formula" to see exactly how your answer was derived, making the result easy to verify and trust.

Flexible Output Options

Round answers to 2 decimal places and optionally display a full summary covering every calculation type for your inputs.

Copy Results and Start Over Instantly

Copy your answer to the clipboard with one click, or reset everything with "Start Over" to run a fresh calculation.

Private and Instant

All math happens locally in your browser — no account, no signup, and no data sent anywhere. It works on desktop and mobile with full dark-mode support.

Why Choose Trencada?

Trencada offers simple, reliable online tools for everyday calculations — from percentages and discounts to health and finance. Every tool on Trencada.com is free, works directly in your browser, and never requires installation or registration. Pair the Percentage Calculator with the Discount Calculator for shopping math, the Tip Calculator for dining out, or the BMI Calculator for health stats.

Frequently Asked Questions

How do I calculate a percentage?

To calculate a percentage of a number, multiply the number by the percentage and divide by 100. For example, 20% of 200 is 40.

How do I calculate percentage increase?

Subtract the original value from the new value, divide the result by the original value, and multiply by 100.

How do I calculate percentage decrease?

Subtract the new value from the original value, divide the result by the original value, and multiply by 100.

How do I calculate a discount?

Multiply the original price by the discount percentage and divide by 100. Subtract the discount amount from the original price to get the final price.

Can I calculate what percentage one number is of another?

Yes. Divide the first number by the second number and multiply the result by 100.

Is the Percentage Calculator free?

Yes. You can calculate percentages online for free using the Trencada Percentage Calculator.

Do I need to install software?

No. The Percentage Calculator works directly in your web browser, so no installation is required.

Does the Percentage Calculator work on mobile?

Yes. The tool is fully responsive and works on phones, tablets, and desktops, with dark-mode support for comfortable use at any time.

Is my data sent to a server when I use it?

No. Every calculation runs 100% in your browser using client-side JavaScript, so your numbers never leave your device.

Frequently Asked Questions

How do I calculate percentage increase?

Use this formula: ((new value - old value) / old value) x 100. For example, if a price rises from $50 to $75: ((75 - 50) / 50) x 100 = 50% increase.

How do I calculate percentage difference between two numbers?

Take the absolute difference between the two numbers, divide by their average, and multiply by 100: (|A - B| / ((A + B) / 2)) x 100. For example, the difference between 80 and 120 is (40 / 100) x 100 = 40%.