Percentage Calculator
Calculate X% of a number, find what percent one value is of another, and work out percentage change, increase, or decrease — each answer shown with the full formula.
- 01Find what is X% of Y in one click — perfect for discounts, tips, and tax.
- 02Work out what percent one number is of another (X is what percent of Y).
- 03Calculate percentage change, increase, and decrease between two values.
- 04See the worked formula behind every result, so you can learn and check it.
- 05100% free and private — every percentage calculation runs in your browser.
Percentage Calculator
Result
30
Step-by-step calculation
- 0115% of 200 = (15 ÷ 100) × 200 = 30
Why Use This Percentage Calculator
Three Calculations in One
A single percentage calculator that handles the three most common questions: what is X% of Y, X is what percent of Y, and the percentage change from one value to another. Switch tabs to get the exact calculation you need without hunting for a different tool.
Percentage Change, Increase & Decrease
Use the percentage change calculator to measure growth or decline between an original and a new value. It tells you the percent difference and whether it is an increase or a decrease — ideal for prices, salaries, scores, and statistics.
Worked Formula on Every Answer
Each result shows the full formula with your numbers plugged in, for example 15% of 200 = (15 ÷ 100) × 200 = 30. See exactly how the percentage is calculated so you can learn the method and double-check your own work.
Discounts, Tips, Tax & Grades
Quickly work out a sale discount, a restaurant tip, sales tax, a commission, an exam percentage, or a markup. Everyday percentage math becomes a one-click job, on desktop or mobile.
Instant and Private
Everything runs entirely in your browser with no server round-trips. Your numbers never leave your device, answers appear instantly, and there is no signup or installation required.
Free with No Limits
Calculate as many percentages as you need — no daily caps, no account, and no paywall. The full percentage calculator is completely free to use.
What Is a Percentage?
A percentage is a way of expressing a number as a fraction of 100. The word percent literally means 'per hundred', so 25% means 25 out of every 100, or 0.25 as a decimal. Percentages make it easy to compare proportions, describe change, and scale quantities up or down, which is why they appear everywhere from shopping discounts and interest rates to test scores and statistics.
Whether you are calculating a discount, a tip, a grade, a growth rate, or a percentage difference, this percentage calculator gives instant answers with the formula shown for every result.
- What Is X% of Y?
- To find a percentage of a number, divide the percentage by 100 and multiply by the number: (X ÷ 100) × Y. For example, 15% of 200 is (15 ÷ 100) × 200 = 30. This is the calculation behind discounts, tips, tax, and commission.
- X Is What Percent of Y?
- To express one number as a percentage of another, divide the part by the whole and multiply by 100: (X ÷ Y) × 100. For example, 30 is (30 ÷ 200) × 100 = 15% of 200. This is how you turn a score or a share into a percentage.
- Percentage Change, Increase & Decrease
- Percentage change compares a new value to an original value: ((new − old) ÷ old) × 100. A positive result is a percentage increase and a negative result is a percentage decrease. For example, going from 200 to 230 is a 15% increase.
- Percentage Difference
- Percentage difference compares two values relative to their average and is always positive, which is useful when neither value is a clear baseline. It differs from percentage change, where the original value is the reference point.
How to Use the Percentage Calculator
- 01
Pick a calculation
Choose the tab that matches your question: 'X% of Y' to find a percentage of a number, 'X is what % of Y' to express one number as a percentage of another, or '% change' to measure the percentage change between two values.
- 02
Enter your two numbers
Type the two values into the labelled input boxes. The labels update for each calculation so you always know which number goes where — for example the percentage and the base, or the original and the new value. Decimals and negative numbers are supported.
- 03
Click Calculate
Press the Calculate button. The tool computes the answer instantly in your browser and, for percentage change, tells you whether the result is an increase or a decrease.
- 04
Read the result and formula
The headline shows your answer in large type. Below it, the step-by-step line shows the full formula with your numbers filled in, such as 15% of 200 = (15 ÷ 100) × 200 = 30, so you can follow and verify the math.
Tips for Calculating Percentages
Choose the Right Mode
Decide what you are actually asking. 'X% of Y' scales a number, 'X is what % of Y' turns a part into a percentage, and '% change' compares before and after. Picking the wrong mode is the most common percentage mistake.
Use the Original as the Base
For percentage change, always divide by the original (starting) value, not the new one. The original is the reference point, so going from 200 to 230 is a 15% increase, while 230 to 200 is about a 13% decrease.
Mind Increase vs Decrease
A percentage increase followed by the same percentage decrease does not return you to the start. A 50% rise then a 50% fall leaves you 25% lower, because each percentage is taken from a different base.
Convert Percentages to Decimals
When chaining calculations, convert percentages to decimals first (divide by 100). To add 20% to a value, multiply by 1.20; to remove 20%, multiply by 0.80. This avoids common rounding and order-of-operations errors.
Percentage vs Percentage Points
Going from 10% to 15% is a rise of 5 percentage points, but a 50% increase in relative terms. Be clear about which one you mean, especially when reporting rates, interest, or statistics.
Keep Enough Precision
Avoid rounding intermediate results too early, as small rounding errors compound. Round only the final percentage for reporting, and keep extra decimals while you are still calculating.
Percentage Formulas and Definitions
Definition of a percentage
A percentage expresses a number as a fraction of 100. The symbol % means 'per hundred', so 40% equals 40/100 = 0.4. Percentages let you compare proportions on a common scale regardless of the original totals.
What you can calculate with percentages
- A percentage of a number — discounts, tips, tax, commission, and markups.
- One number as a percentage of another — scores, shares, and proportions.
- Percentage change between two values — growth, decline, and rates.
- Percentage increase and decrease — price rises, pay cuts, and adjustments.
Percentage, decimal, and fraction
To convert a percentage to a decimal, divide by 100 (25% = 0.25); to convert a decimal to a percentage, multiply by 100. A percentage is also a fraction out of 100, so 25% = 25/100 = 1/4.
Key Percentage Formulas
Percentage of a number
Result = (X ÷ 100) × Y
Example: 15% of 200 = (15 ÷ 100) × 200 = 30.
X is what percent of Y
Percent = (X ÷ Y) × 100
Example: 30 is (30 ÷ 200) × 100 = 15% of 200.
Percentage change
Change % = ((new − old) ÷ old) × 100
Example: 200 → 230 = ((230 − 200) ÷ 200) × 100 = 15% increase.
Percentage increase
Increase % = ((new − old) ÷ old) × 100, when new > old
Example: 50 → 75 = (25 ÷ 50) × 100 = 50% increase.
Percentage decrease
Decrease % = ((old − new) ÷ old) × 100, when new < old
Example: 80 → 60 = (20 ÷ 80) × 100 = 25% decrease.
Percentage difference
Difference % = (|A − B| ÷ ((A + B) ÷ 2)) × 100
Compares two values relative to their average; always positive.
Percentage Calculator FAQ
Q01How do I calculate a percentage of a number?
To find X% of a number Y, divide the percentage by 100 and multiply by the number: (X ÷ 100) × Y. For example, 15% of 200 is (15 ÷ 100) × 200 = 30. Use the 'X% of Y' tab and the calculator does this for you and shows the formula.
Q02How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100: (X ÷ Y) × 100. For example, 30 out of 200 is (30 ÷ 200) × 100 = 15%. Use the 'X is what % of Y' tab to get the answer and the worked steps instantly.
Q03How do I calculate percentage change?
Percentage change is ((new value − original value) ÷ original value) × 100. For example, going from 200 to 230 is ((230 − 200) ÷ 200) × 100 = 15%, an increase. A negative result means a percentage decrease. Use the '% change' tab for this calculation.
Q04What is the difference between percentage change and percentage difference?
Percentage change measures the move from an original value to a new value relative to the original, and can be positive (increase) or negative (decrease). Percentage difference compares two values relative to their average and is always positive. Use percentage change when one value is a clear starting point.
Q05How do I calculate a percentage increase or decrease?
Subtract the original value from the new value, divide by the original value, then multiply by 100. A positive result is a percentage increase and a negative result is a percentage decrease. The '% change' tab labels the result as an increase or a decrease automatically.
Q06Can I enter decimals and negative numbers?
Yes. You can enter integers, decimals, and negative numbers in either field, and you may include a trailing percent sign such as 15%. The calculator parses the values and shows the result with the full formula.
Q07Is my data sent to a server?
No. The percentage calculator runs entirely in your browser using JavaScript. Your numbers are never uploaded or stored anywhere, so it is safe to use with private or sensitive figures.
Q08Is this percentage calculator free?
Yes, it is completely free with no limits, no signup, and no premium tier. Calculate percentages, percentage change, increase, and decrease as many times as you like.