Percentage Calculator

About Our Percentage Calculator

Percentages are everywhere. Discounts in a sale, interest on a loan, tips at a restaurant, exam scores, tax rates, salary hikes, body fat, battery level, polling data — all use percentages. Yet despite how often we use them, calculating percentages manually is surprisingly error-prone. A misplaced decimal or an extra zero can turn a 15% discount into a 150% markup.

Our percentage calculator handles five of the most common percentage problems in one place, with a clear step-by-step breakdown of each calculation. Whether you are a student, shopper, business owner, or anyone who needs quick math, this tool gives you accurate answers in seconds — completely in your browser.

Five Percentage Modes Explained

The tool covers the five most common percentage problems:

1. What is X% of Y? — Find a specific percentage of a number. Example: What is 15% of 200? Answer: 30. This is the most common type of calculation — used for discounts, tips, and interest.
2. X is what % of Y? — Find what percentage one number is of another. Example: 45 is what % of 60? Answer: 75%. Useful for exam scores, proportions, and ratios.
3. Percentage Increase / Decrease — Measure the percent change between two values. Example: going from 80 to 100 is a 25% increase. Useful for tracking growth, inflation, or losses.
4. Add % to number — Increase a number by a given percentage. Example: Add 20% to 500 = 600. Perfect for calculating final prices after tax.
5. Subtract % from number — Decrease a number by a given percentage. Example: subtract 25% from 400 = 300. Useful for discount calculations.

How to Use the Percentage Calculator

Using the tool is intuitive:

1. Choose the mode that matches your problem — one of the five tabs above.
2. Enter the numbers in the inline input fields. Each field corresponds to a specific role (e.g. "X%" and "Y").
3. Click "Calculate" and the answer appears instantly, along with the formula used.
4. See the step-by-step explanation — understand exactly how the calculation was performed, useful for learning or double-checking.

Why Use Our Percentage Calculator

Many percentage calculators exist online, but ours offers some practical advantages:

• Five modes in one tool. Instead of using separate pages for each calculation, all five most common percentage problems are available as tabs.
• Step-by-step explanations. Every result is broken down into individual steps, so you can verify the math or learn how it works.
• Precise formula display. The exact formula used is shown below the result, so you can see exactly how the number was derived.
• Privacy first. All calculations happen in your browser. Your numbers are never sent to a server, logged, or stored.
• Works with decimals and negative numbers. Not limited to whole numbers — handles any realistic input.

Common Uses for Percentage Calculations

Percentages are used everywhere in daily life. Some of the most common uses:

• Calculating shopping discounts (e.g. 30% off a ₹2,000 item)
• Adding or removing sales tax or VAT from a price
• Figuring out tip amounts at restaurants
• Calculating test scores and grades (e.g. 45 out of 60 = 75%)
• Tracking salary increases or raises (e.g. 8% hike)
• Computing interest rates for loans and credit cards
• Understanding inflation and price changes over time
• Analyzing business growth or revenue decline
• Reading statistics and polling data correctly
• Calculating body fat percentages or fitness progress

Essential Percentage Formulas

If you need to calculate percentages manually, here are the key formulas:

• X% of Y: (X ÷ 100) × Y
• X is what % of Y: (X ÷ Y) × 100
• Percent change from A to B: ((B − A) ÷ |A|) × 100
• Add X% to Y: Y × (1 + X ÷ 100)
• Subtract X% from Y: Y × (1 − X ÷ 100)

While these formulas are simple, it is easy to make mistakes — especially with negative numbers or when the base value is unclear. Our calculator eliminates the guesswork.

Frequently Asked Questions

What is a percentage?

A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin "per centum" meaning "by the hundred." For example, 25% means 25 out of every 100, or 0.25 in decimal form. Percentages are used everywhere — discounts, interest rates, test scores, statistics, and more.

How do I calculate X% of a number?

To find X% of a number Y, multiply Y by X and divide by 100. The formula is: (X ÷ 100) × Y. For example, 15% of 200 = (15 ÷ 100) × 200 = 0.15 × 200 = 30. Our "What is X% of Y?" mode does this calculation automatically.

How do I find what percentage one number is of another?

Divide the first number by the second, then multiply by 100. Formula: (X ÷ Y) × 100. For example, if you scored 45 out of 60 on a test, your percentage is (45 ÷ 60) × 100 = 75%. Use our "X is what % of Y?" mode for this.

How do I calculate percentage increase or decrease?

Subtract the old value from the new value, divide by the old value, then multiply by 100. Formula: ((New − Old) ÷ |Old|) × 100. A positive result is an increase; a negative result is a decrease. For example, going from 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25% increase.

What is the difference between percentage and percentage points?

Percentage points measure absolute change, while percentage measures relative change. If interest rates go from 4% to 6%, that is a 2 percentage point increase — but a 50% relative increase. Confusing the two is a common error in news reporting, especially in finance and statistics.

How do I add or subtract a percentage from a number?

To add X% to Y, calculate X% of Y and add it: Y + (X ÷ 100) × Y. Equivalently, multiply Y by (1 + X÷100). To subtract, use Y − (X ÷ 100) × Y, or multiply by (1 − X÷100). Our "Add %" and "Subtract %" modes do both instantly.

Is my calculation data stored or shared?

No. All calculations happen entirely in your browser using JavaScript. Your numbers are never sent to a server, logged, or shared. This is completely private — even if you disconnect from the internet, the calculator continues to work.

Can I use decimals and negative numbers?

Yes. Our calculator accepts any real number, including decimals (like 12.5%) and negative values (useful for tracking losses or decreases). The step-by-step explanation will show you how negative values are handled in the formula.

Related Tools You Might Find Useful

If you found this percentage calculator helpful, you might also want to try our tip calculator for restaurant gratuity, our loan calculator for EMI and interest calculations, or our BMI calculator for health tracking.