Percentage Calculator
Find a percent of a number, what percent one number is of another, or a percentage increase or decrease — pick a mode and get an instant result.
Choose a calculation
Please enter valid numbers to calculate.
Result
20% of 150 is:
Resensies
How to use the percentage calculator
- Pick the calculation you need: percent of a number, what percent one number is of another, percentage change, or increase/decrease by a percent.
- Enter your numbers — decimals and negative numbers are both fine.
- Read the result instantly, updated as you type.
Percentage formulas explained
Each mode above uses a standard formula. Here's what the calculator is doing behind the scenes for each one.
Percentage formulas at a glance
| Calculation | Formula | Example |
|---|---|---|
| X% of Y | (X ÷ 100) × Y | 20% of 150 = 30 |
| X is what % of Y | (X ÷ Y) × 100 | 30 is 75% of 40 |
| % change from X to Y | ((Y − X) ÷ X) × 100 | 80 to 100 is a 25% increase |
| Increase X by P% | X × (1 + P ÷ 100) | 80 increased by 25% = 100 |
| Decrease X by P% | X × (1 − P ÷ 100) | 80 decreased by 25% = 60 |
Gereelde vrae
Is this percentage calculator really free, with no sign-up?+
Yes. The percentage calculator runs entirely with JavaScript in your browser, so there is no account, no API key, and no limit on how many times you can use it.
Does my data get uploaded anywhere?+
No. All numbers you enter are processed locally on your device. Nothing is sent to a server, stored, or logged.
How do I calculate 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.
How do I find what percent one number is of another?+
Divide the first number by the second number, then multiply by 100. For example, 30 out of 40 is (30 / 40) x 100 = 75%.
Can this calculator handle negative numbers?+
Yes. The calculator accepts negative numbers and decimals in every mode, and shows the correctly signed result.
How do I calculate a percentage discount or percent off?+
Use the "Increase/decrease by %" mode, enter the original price, choose Decrease, and enter the discount percentage to get the sale price.
How do I find the original price before a discount?+
Use the "X is what % of Y" mode with the sale price and the percentage you paid (100 minus the discount) to work back to the original price.
Tools for Everyday Math
How This Calculator Works
Every mode runs the standard percentage formulas directly in your browser using JavaScript — no numbers are ever sent to a server. Results update live as you type, using the current calculation mode you've selected.
Laaste opdatering: 28 Augustus 2026.
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