Percentage Calculator

Percent of a number, change, difference and original value

Percentage (%)

Number

100

Try an example

Result

5% of 100 = 5

0%50%100%

Decimal form

0.05

Number + 5%

105

Number − 5%

Working

(5 ÷ 100) × 100 = 5

To work out a discount or tax, take the percentage of the price, then subtract it or add it to the price.

Percentage Calculator — Free Percentage Increase, Decrease and Difference Calculator on HighCalc

Percentage Calculator: Free Online Percentage Increase, Decrease & Difference Calculator

The Percentage Calculator is a free online tool that helps you quickly calculate percentages, percentage increase, percentage decrease, percentage difference, and original values. Whether you are solving school math problems, calculating discounts while shopping, analyzing financial growth, or comparing values, this calculator provides fast and accurate results instantly.

It includes five calculation modes: percentage of a number, percent change, find the percentage, original value and percentage difference. It is mobile-friendly, easy to use, and designed for students, teachers, business owners, accountants, and everyday users.

Quick answer: 20% of 150 is 30. A move from 100 to 120 is a 20% increase, 15 is 20% of 75, a price of 120 after a 20% rise started at 100, and 80 and 100 differ by 22.22%. Pick the tab that matches your question, type your numbers and the result appears as you type.

What Is a Percentage?

A percentage is a value expressed out of 100, and the word percent means per hundred. So 50% means 50 out of 100, 25% means 25 out of 100, and 100% means the complete value. Percentages make numbers easy to compare because they put different quantities on the same scale, which is why they appear in shopping discounts, school grades, taxes, banking, finance, statistics, business growth, investments, population studies and data analysis.

Five Percentage Calculations in One Tool

The first tab finds a percentage of a number and shows the number plus and minus that percentage. The % Change tab gives the percent change between two values, Find % turns a part and a whole into a percentage, Original Value works backwards from a final amount, and % Difference compares two values using their average. Every tab has sliders and shows its working.

Percentage Formulas

These are the formulas behind each tab. The calculator applies them for you, but knowing them helps you check results by hand.

PercentagePercentage = (Part ÷ Whole) × 100

Percentage of a numberResult = (Percentage ÷ 100) × Number

Percentage increase or decreaseChange % = ((New value − Original value) ÷ Original value) × 100

Original valueOriginal = Final value ÷ (1 ± Percentage ÷ 100)

Percentage differenceDifference % = (|A − B| ÷ ((A + B) ÷ 2)) × 100

Use plus in the original value formula when the final value came after an increase and minus when it came after a decrease.

Percentage Examples

Calculation	Example	Result
Percentage of a number	20% of 150	30
Percentage increase	100 → 120	20% increase
Percentage decrease	100 → 80	20% decrease
Percentage decrease	120 → 100	16.67% decrease
Find the percentage	15 out of 75	20%
Original value	120 after a 20% increase	100
Percentage difference	80 and 100	22.22%

Notice that 100 to 120 is a 20% increase, but 120 back to 100 is only a 16.67% decrease. The percentage is always measured against the starting value, so the same gap gives a different percentage in each direction. An $80 item with 25% off saves $20 and costs $60, and 8% tax on $50 adds $4.

Where Percentages Are Used Every Day

Shoppers use them to compare sale prices. Students turn marks into a score with the grade calculator and combine results with the GPA calculator. In money matters, percentages describe rates, returns and fees, and the interest calculator builds on the same ideas. When a ratio is easier to read as a fraction, the fraction calculator handles the conversion.

Limits and Common Mistakes

A percentage change needs a starting value that is not zero, and a decrease of 100% or more cannot be reversed to find an original value, so the calculator shows a message in those cases. Do not mix up percent with percentage points: moving from 10% to 15% is a rise of 5 percentage points but a 50% increase. Results are mathematical, so for tax, legal or investment decisions check the exact rules and rounding that apply to you.

Who Can Use This Calculator?

Students and teachers use it for homework and classroom demonstrations. Accountants, business owners, financial analysts and ecommerce sellers use it for margins, taxes and growth figures, while investors, researchers, freelancers and online shoppers use it to compare values and check discounts.

How to Use This Percentage Calculator

Choose a calculation

Pick % of a Number, % Change, Find %, Original Value or % Difference. Example: 20% of 150 = 30.

Enter your values

Type the numbers or move the sliders. For % Change enter the original and new value, such as 100 and 120 for a 20% increase.

Read the result

The answer, three extra figures and the working appear right away and update as you type.

Try an example

Tap an example under the button to fill the fields, then change the numbers to your own.

Features

Instant Results

Everything updates the moment you change a value

Five Calculations

Percent of a number, change, find %, original value and difference

Interactive Sliders

Adjust values quickly, or type exact numbers

Clear Working

See the formula with your numbers filled in

Works Everywhere

Fully responsive on phone, tablet, and desktop

Private & Secure

All calculations run in your browser — nothing is stored

Frequently Asked Questions

Common questions about the Percentage Calculator.

How do I calculate a percentage of a number?

Enter the percentage and the base number in the first tab. The calculator divides the percentage by 100 and multiplies it by the number, so 20% of 150 equals 30. It also shows the number plus and minus that percentage, which is handy for taxes and discounts.

How do I calculate percentage increase or decrease?

Enter the original value and the new value in the % Change tab. The calculator subtracts the original from the new value, divides by the original and multiplies by 100. Going from 100 to 120 is a 20% increase, and going from 100 to 80 is a 20% decrease.

What is the formula for percentage?

The standard percentage formula is (Part ÷ Whole) × 100. For example, 15 out of 75 is (15 ÷ 75) × 100, which is 20%. The Find % tab does this for you and shows the working.

How is percentage difference different from percentage change?

Percentage change measures movement from an original value, so direction matters. Percentage difference compares two values equally by dividing their gap by their average, so the order does not matter. For 80 and 100 the difference is 22.22%, while a change from 80 to 100 is 25%.

How do I find the original value before a percentage increase?

Use the Original Value tab, enter the final value and the percentage, and choose Increase or Decrease. For an increase the calculator divides the final value by 1 plus the rate, so 120 after a 20% increase was 100. For a decrease it divides by 1 minus the rate.

Can I calculate discounts with this calculator?

Yes. Enter the discount percentage and the original price in the first tab. The result is the amount saved and the Number minus percentage tile is the sale price, so 25% off 80 is 20 saved and a final price of 60. To undo a discount and find the original price, use the Original Value tab with Decrease selected.