Percentage Calculator – Find X% of Y, Increase & Decrease
Calculate percentages instantly. Find X% of Y, percentage increase/decrease. No manual math. Free percentage tool.
How to use this percentage calculator
- Choose a calculation type: "X% of Y", "Increase by X%", or "Decrease by X%".
- Enter the number (or original value) in the first input field.
- Enter the percentage you want to apply in the second input field.
- Click the "Calculate" button.
- Read the resulting value along with the plain-language summary of the calculation.
- Change the calculation type or values at any time and recalculate as needed.
Frequently Asked Questions
What types of percentage calculations can I do?
You can calculate: percentage of a number (X% of Y), percentage increase, and percentage decrease.
How do I calculate percentage increase?
Enter the original value and the percentage increase. The result will be the new value after the increase.
Can I calculate percentage decrease?
Yes, select "Percentage Decrease" and enter the original value and percentage. The result will be the new value after the decrease.
Related Tools
A percentage calculator helps shoppers, students, employees, and analysts quickly work out percentage-based values without doing the math by hand. This tool is useful for finding a discount amount during a sale, checking a tip or tax on a bill, working out a salary raise or pay cut, comparing exam or survey scores, or estimating growth between two figures. By using a percentage calculator, you can avoid manual arithmetic errors and get an instant, accurate answer for everyday number problems. The tool supports three common calculation types — a percentage of a number, a percentage increase, and a percentage decrease — all computed instantly and entirely in your browser for privacy and speed.
What is percentage calculator?
A percentage calculator is a utility that applies one of three formulas depending on what you need. To find X% of Y, it multiplies the number by the percentage and divides by 100. To calculate a percentage increase, it multiplies the original value by one plus the percentage divided by 100, giving the new, larger value. To calculate a percentage decrease, it multiplies the original value by one minus the percentage divided by 100, giving the new, smaller value. Each calculation type uses the same two inputs — a number and a percentage — but interprets them differently based on the selected mode. The result and a plain-language summary are displayed immediately after calculating, with all math performed locally in your browser.
Common use cases
- Working out the discount amount and final price during a sale
- Calculating a tip or sales tax on a restaurant bill
- Figuring out a salary raise or pay cut as a new take-home amount
- Comparing exam scores, grades, or survey results expressed as percentages
- Estimating growth or decline between two numbers, such as sales or website traffic
- Splitting a commission or bonus that is defined as a percentage of a total
Limitations and common mistakes
- Supports only single-step percentage calculations (of, increase, decrease); it does not chain multiple percentage changes together automatically.
- Displayed results are rounded to at most two decimal places, so extremely precise figures may appear slightly rounded on screen.
- The percentage is entered as a plain number (e.g. 10 for 10%), not as a decimal fraction, so entering 0.1 would be treated as 0.1%, not 10%.
- The tool is currency- and unit-agnostic — it works purely with numbers and does not add currency symbols or formatting.
- Basic input validation only checks for valid numbers; it does not restrict negative values, so unusual inputs will still produce a mathematically valid but possibly nonsensical result.