About the Percentage Calculator
Need to work out 15% of 80, what percent 45 is of 300, or how much a price grew between two months? This percentage calculator answers all three questions with dedicated modes: percent of a number, X is what percent of Y, and percentage change. Pick a tab, type two numbers, and the answer appears instantly — no formulas to remember and no spreadsheet required.
Because everything runs in your browser, results update the moment you type; nothing is sent to a server and there is no sign-up. Students use it to check homework, shoppers to compare deals, and analysts to sanity-check growth figures. The change mode returns a signed result, so a drop from 80 to 60 reads clearly as −25% rather than leaving you to guess the direction.
Features
- Three modes: percent of, reverse percent, change
- Signed results distinguish increases from decreases
- Answers update instantly as you type
- Clean rounding to three decimal places
- Free with no account or installation
- All math runs privately in your browser
How to calculate a percentage
- Choose a mode: % of a number, X is what % of Y, or % change.
- Enter your two values in the input fields.
- Read the result — it updates live as you type.
- Switch tabs to answer a different percentage question with the same numbers.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number: X% of Y equals (X ÷ 100) × Y. For example, 15% of 80 is 0.15 × 80 = 12. The calculator's first tab applies exactly this formula and shows the answer as soon as both values are entered.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100: (part ÷ whole) × 100. So 45 out of 300 is (45 ÷ 300) × 100 = 15%. Use the middle tab, enter the value first and the total second, and the percentage appears immediately.
What is the percentage change formula?
Percentage change equals ((new − old) ÷ old) × 100. Going from 80 to 60 gives ((60 − 80) ÷ 80) × 100 = −25%, a decrease, while 60 to 80 gives +33.333%, an increase. The change tab computes this and keeps the plus or minus sign so the direction is obvious.
What is the difference between percentage change and percentage points?
Percentage points measure a simple difference between two percentages, while percentage change is relative to the starting value. If a rate moves from 10% to 12%, that is 2 percentage points but a 20% percentage change. Use the change mode when you want the relative figure.
Is this percentage calculator free, and is my data safe?
Yes. It is completely free, requires no sign-up, and every calculation happens locally in your browser — the numbers you type are never uploaded to any server. Once the page has loaded it even keeps working offline, and it behaves identically on desktop, tablet or phone.