Instant Math

Free Online Percentage Calculator

Quickly solve all common percentage questions in one intuitive place. Calculate percentage of a number, find percentage change (increase/decrease), and calculate ratio percentages in real time.

Perfect for students, accountants, business owners calculating sales tax and discounts, or anyone needing quick mathematical answers.

Calculate a percentage portion of any number

1. What is X% of Y?

Calculate a percentage portion of any number

ofis

Formula: (15 ÷ 100) × 200 = 30

2. X is what % of Y?

Find the proportion ratio between two values

isof=

25%

Formula: (25 ÷ 100) × 100 = 25%

3. Percentage Change (from X to Y)

Calculate percentage increase or decrease

fromto=

+25%

Formula: ((100 - 80) ÷ 80) × 100 = +25%

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How It Works (Step-by-Step)

1. Select Calculation Mode

Choose between "What is X% of Y?", "X is what % of Y?", or "Percentage Increase / Decrease".

2. Enter Your Numbers

Type your numbers into the input boxes. The calculator computes the result instantly as you type.

3. View Step-by-Step Formula

Review the instant calculation result along with the mathematical breakdown explaining the answer.

Key Features & Advantages

Instant Real-Time Answers

Results update automatically on every keystroke with zero delay or page reloads.

All-in-One Calculations

Covers standard percentages, discounts, percentage change, markups, and differences.

Visual Mathematical Steps

Provides clear explanations and formula steps so you can understand the underlying math.

Mobile Friendly & Free

Optimized for mobile touchscreens and desktop screens with no ads blocking your inputs.

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Frequently Asked Questions

How do you calculate a percentage of a number?

Multiply the number by the percentage fraction (P / 100). For example, 20% of 150 = (20 / 100) * 150 = 30.

How do you calculate percentage increase or decrease?

Subtract the old value from the new value, divide by the absolute old value, and multiply by 100: ((New - Old) / Old) * 100.

Is this calculator free to use?

Yes, 100% free with no limits, no login, and no payment required.

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