Math

Percentage Calculator

Calculate percentages, percentage change, and reverse percentages instantly.

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Percentage Calculator

Calculation Type

Percentage

Value

Results

How to Use Percentage Calculator

1 Select your calculation type from the dropdown (X% of Y, What percent, or Percent change)
2 Enter the percentage and value in the respective fields
3 Click Calculate to get instant results
4 Use the Reset button to clear and start a new calculation

Formula & Methodology

Percentage of a Number: Result = (Percentage ÷ 100) × Value

What Percent: Percentage = (Part ÷ Total) × 100

Percent Change: Change% = ((New - Old) ÷ |Old|) × 100

About Percentage Calculator

A percentage calculator is one of the most versatile mathematical tools you can use daily. Whether you're calculating discounts while shopping, figuring out tax amounts, analyzing data changes, or solving math problems, percentages are everywhere.

What is a Percentage?

A percentage is a fraction expressed as parts per hundred. The word comes from Latin "per centum" meaning "by the hundred." When we say 25%, we mean 25 out of every 100, or 25/100 = 0.25.

Types of Percentage Calculations

1. Finding X% of Y: This is the most common use. To find 15% of 200, multiply 200 by 0.15 to get 30.

2. Finding What Percent X is of Y: Divide the part by the whole and multiply by 100. Example: 30 is what percent of 200? Answer: (30/200) × 100 = 15%.

3. Percentage Change: Used to measure increase or decrease. Formula: ((New - Old) / Old) × 100.

Complete Guide

What Is a Percentage?

A percentage is simply a ratio out of 100. The word itself comes from the Latin per centum, meaning "per hundred." When you say something is 45%, you mean 45 out of every 100 — or equivalently, 45/100 = 0.45 as a decimal.

Percentages appear everywhere in daily life: sales discounts, bank interest rates, exam scores, tax rates, nutritional labels, and weather forecasts. Mastering the three core percentage formulas will make you faster and more confident in all these situations.

The Three Core Percentage Formulas

1. Finding a Percentage of a Number

Formula: Result = (Percentage / 100) × Number

Example: What is 30% of 250?
Result = (30 / 100) × 250 = 0.30 × 250 = 75

2. Finding What Percentage One Number is of Another

Formula: Percentage = (Part / Whole) × 100

Example: What percentage is 45 of 180?
Percentage = (45 / 180) × 100 = 0.25 × 100 = 25%

3. Finding the Original Value

Formula: Original = Value / (Percentage / 100)

Example: ₹840 is 70% of what number?
Original = 840 / 0.70 = ₹1,200

Percentage Increase and Decrease

To calculate percentage change:
% Change = ((New − Old) / |Old|) × 100

If New > Old, it's an increase. If New < Old, it's a decrease.

Example: A salary rose from ₹40,000 to ₹46,000.
% Increase = ((46,000 − 40,000) / 40,000) × 100 = (6,000 / 40,000) × 100 = 15%

Real-World Applications

Shopping discounts: 25% off ₹1,200 = ₹900 final price
GST calculation: 18% GST on ₹1,000 = ₹180 tax, ₹1,180 total
Grade calculation: 78 out of 120 = 65% score
Bank interest: 7% per annum on ₹50,000 = ₹3,500/year interest
Weight change: Lost 5 kg from 80 kg = 6.25% weight loss

Quick Mental Math Tips

To find 10% — move the decimal point one place left (10% of 350 = 35).

To find 5% — find 10% then halve it (5% of 350 = 17.5).

To find 20% — double the 10% value (20% of 350 = 70).

To find 15% — add 10% and 5% (15% of 350 = 35 + 17.5 = 52.5).

To find 1% — move the decimal two places left (1% of 350 = 3.5).

Common Mistakes to Avoid

Percentage vs. Percentage Points: If an interest rate rises from 5% to 8%, it rose by 3 percentage points. But it rose by 60% (as a percentage change).

Stacking Discounts: Two 20% discounts do not equal 40% off. Applying 20% off twice to ₹100: first 20% gives ₹80; second 20% of ₹80 gives ₹64. The effective discount is 36%, not 40%.

Use our free Percentage Calculator to instantly handle all these calculations without error.

Frequently Asked Questions

A percentage is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign "%". For example, 45% means 45 out of every 100, or 45/100 = 0.45.

To find what percentage A is of B, use the formula: (A ÷ B) × 100. For example, to find what percentage 25 is of 200: (25 ÷ 200) × 100 = 12.5%.

To find X% of a number N, multiply N by X and divide by 100. For example, 30% of 150 = (150 × 30) ÷ 100 = 45.

Percentage increase = ((New Value − Old Value) ÷ Old Value) × 100. For example, if a price rises from $80 to $100, the increase is ((100 − 80) ÷ 80) × 100 = 25%.

Percentage decrease = ((Old Value − New Value) ÷ Old Value) × 100. For example, if a price drops from $100 to $75, the decrease is ((100 − 75) ÷ 100) × 100 = 25%.

A percentage point is the arithmetic difference between two percentages. If an interest rate rises from 5% to 8%, it has risen by 3 percentage points (not 3%). Expressed as a percentage change, it is a 60% increase.

To find the original value before a percentage change, divide the final value by (1 + percentage/100) for an increase, or (1 − percentage/100) for a decrease. Example: if $120 is 20% more than original, original = 120 ÷ 1.20 = $100.

Yes. A percentage greater than 100% means the value exceeds the reference. For example, if your profit is 150% of your investment, your profit is 1.5 times the investment amount.

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