What is X% of Y?

What is % of ?

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Formula: Result = (X / 100) × Y

X is what percent of Y?

is what % of ?

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Formula: Percentage = (X / Y) × 100

Percentage Change

From to

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Formula: Change = ((New - Old) / |Old|) × 100

Percentage Increase & Decrease

What is increased/decreased by %?

Increased

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Decreased

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Increase: X × (1 + P/100) | Decrease: X × (1 - P/100)

Percentage Difference

Value 1: Value 2:

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Formula: Difference = |A - B| / ((|A| + |B|) / 2) × 100

Percentage Calculator Guide

How to Calculate Percentages

A percentage represents a fraction of 100. To find what X% of a number is, multiply the number by X/100. For example, 15% of 200 = 200 × 0.15 = 30. Our calculator handles five common percentage calculations instantly.

Percentage Increase Calculator

To calculate percentage increase: multiply your number by (1 + percentage/100). For example, 200 increased by 25% = 200 × 1.25 = 250. This is commonly used for salary raises, price increases, and growth calculations.

Percentage Change Calculator

Percentage change measures how much a value has increased or decreased relative to the original. The formula is: ((New Value - Old Value) / |Old Value|) × 100. A positive result means increase, negative means decrease.

Percentage Difference vs Percentage Change

These are often confused but serve different purposes:

Percentage Change measures change from one specific value to another (directional — has a "from" and "to")
Percentage Difference measures how different two values are regardless of direction (symmetric — the order doesn't matter)

Use percentage change when comparing a before/after scenario. Use percentage difference when comparing two independent values.

Calculator	Formula	Example
X% of Y	(X/100) × Y	20% of 150 = 30
X is what % of Y	(X/Y) × 100	30 is 20% of 150
% Change	((New-Old)/\|Old\|) × 100	50 to 75 = +50%
% Increase	X × (1 + P/100)	100 + 25% = 125
% Decrease	X × (1 - P/100)	100 - 25% = 75
% Difference	\|A-B\|/((\|A\|+\|B\|)/2) × 100	80 vs 120 = 40%

Common Percentage Problems

Tip calculation: What is 18% of $45? Answer: $8.10
Discount: $80 decreased by 30%? Answer: $56
Grade percentage: 42 out of 50? Answer: 84%
Sales growth: Revenue went from $10,000 to $13,500? Answer: +35% change

Why Use This Percentage Calculator?

Our free calculator covers five essential percentage calculations in one place. Results update instantly as you type — no buttons to click. Each calculator shows the formula used, so you can understand the math behind the answer. Works on any device, no sign-up required.