~/devtools / percent
tool::percent

Percentage Calculator

Calculate percentage change, percentages, and discounts in real time. Just enter numbers and get instant results.

ad · 728×90
Change amount
—
Change rate
—
ad · 300×250
// about this tool

About this tool

Percentage calculations appear in nearly every area of daily life and business — from shopping discounts to investment returns, salary negotiations, and grade conversions. This tool bundles three calculators in one place so you can handle any common percentage task instantly.

The Percentage Change tab calculates the absolute difference and the relative rate between two numbers at once. The Percent tab covers three common operations: finding Y% of X, finding what percentage X is of Y, and computing the result of increasing or decreasing X by Y%. The Discount tab works both ways: enter a price and discount rate to find the sale price, or enter a price and sale price to find the discount rate.

All calculations run entirely in your browser in real time. Results update as you type, and a copy button lets you grab any value with one click.

Use cases
  • ▸Instantly calculate the actual price of a 30%-off product while shopping online
  • ▸Work out salary raise amount and rate during job negotiations
  • ▸Calculate ROI for stock or real estate investments
  • ▸Convert a raw test score to a percentage out of 100
  • ▸Analyze year-over-year revenue growth or inflation rate
FAQ
Q. What is the difference between change amount and change rate?
Change amount is the absolute difference between the new and original values. Change rate is that difference expressed as a percentage of the original. For example, 100 → 150 gives a change amount of +50 and a change rate of +50%.
Q. Is a negative result normal?
Yes. If the new value is smaller than the original, the result is negative, indicating a decrease. For example, 100 → 80 gives a change amount of -20 and a change rate of -20%.
Q. How are decimal results handled?
Results are displayed to two decimal places. For example, a discount rate may show as 33.33%. The copy button copies the displayed value exactly.