Everything runs locally in your browser. Your numbers are never uploaded or stored, results update on every keystroke, and each answer shows the worked formula with your values substituted in - so you can check the math or reuse it by hand. It works offline once the page has loaded.
Free Percentage Calculator
Runs entirely in your browser - no upload, no sign-up.
Three ways to ask
Percentage of a number
What is % of ?
2025 × 80 ÷ 100 = 20
What percent is it
is what percent of ?
20%30 ÷ 150 × 100 = 20%
Percentage change
From to is
+25%(50 - 40) ÷ |40| × 100 = +25% · increase
Results update as you type. Decimals (with a dot or a comma) and negative numbers are fine - nothing is uploaded.
How do you calculate a percentage?
To calculate a percentage, divide the part by the whole and multiply by 100: (part ÷ whole) × 100. This free percentage calculator solves the three everyday percent problems live - what is X% of a number, what percent one number is of another, and the percentage increase or decrease between two values.
How to use
- 1Pick the row that matches your question. The calculator shows three fill-in-the-blank sentences: percentage of a number, what percent one number is of another, and percentage change from one value to another.
- 2Type your two numbers. Fill both blanks in that sentence. Decimals (dot or comma) and negative numbers work, and the result updates as you type.
- 3Read and copy the result. The answer appears next to the sentence with the worked formula underneath. Percentage change is labeled as an increase or a decrease. Use Copy to grab the value.
Who it's for
- Shoppers working out a 25% discount, a tip, or how much a price actually rose after two increases.
- Students converting test marks into percentages and checking percentage-change homework against the worked formula.
- Small-business owners figuring margins, VAT or sales tax amounts, and month-over-month revenue change.
- Investors and savers measuring how much a portfolio, price, or balance went up or down in percent terms.
- Anyone comparing numbers - poll results, weight change, battery capacity - who wants the percent, not just the difference.
FAQ
Is this percentage calculator free?
Yes - 100% free, no sign-up, and no limits. All three calculators run entirely in your browser, so they also work offline once the page has loaded.
Are my numbers uploaded anywhere?
No. The math happens locally on your device with plain JavaScript. Nothing you type is sent to a server, stored, or shared - close the tab and it is gone.
How do I calculate the percentage of a number?
Multiply the number by the percent and divide by 100: P% of X = P × X ÷ 100. For example, 25% of 80 is 25 × 80 ÷ 100 = 20. The first row of the calculator does exactly this and shows the substitution.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100: (part ÷ whole) × 100. For example, 30 of 150 is 30 ÷ 150 × 100 = 20%. If the whole is 0 the answer is undefined - you cannot divide by zero.
How is percentage increase or decrease calculated?
Take the difference, divide by the absolute starting value, and multiply by 100: (new − old) ÷ |old| × 100. Going from 40 to 50 is (50 − 40) ÷ 40 × 100 = +25%, an increase; from 50 to 40 is −20%, a decrease.
What is the difference between percent change and percentage points?
Percent change is relative to the starting value; percentage points are the plain difference between two percentages. If a rate moves from 10% to 15%, that is a rise of 5 percentage points but a 50% increase - saying which one you mean avoids a very common misreading.
Why doesn't a 50% decrease cancel a 50% increase?
Because each step is measured against a different base. 100 up 50% is 150, but 150 down 50% is 75, not 100. The smaller the base, the bigger the percent a fixed change represents - that is why a 50% loss needs a 100% gain to recover.