Percentage Calculator

The Percentage Calculator handles every common percentage operation in one place: find what percent one number is of another, calculate a percentage of a given number, determine the percentage increase or decrease between two values, and reverse-engineer the original price before a discount was applied. Enter your numbers into the relevant fields and the result appears instantly — no manual formula rearranging required. The tool is designed for speed and clarity: each mode is labeled in plain language so you can pick the right calculation without remembering whether you need to multiply or divide. Percentage math comes up constantly in everyday life and professional work — calculating sales tax, figuring out tip amounts, measuring month-over-month revenue growth, grading exam scores, applying or removing discounts, computing profit margins, and analyzing statistical data. Students working through algebra, business owners reviewing financial reports, shoppers comparing sale prices, teachers grading papers, and data analysts computing rate changes will all reach for this tool regularly. The underlying math is straightforward — percent of a number is (P/100) × N, percent change is ((New − Old) / Old) × 100, and reverse percentage is Final / (1 − Discount/100) — but doing it by hand invites rounding errors and sign mistakes, especially under time pressure. The calculator eliminates those mistakes and returns results with clear, consistent decimal precision. All arithmetic runs locally in your browser; the numbers you enter are never transmitted or stored. There is no account required, no advertising, and no usage limit. Bookmark it as your everyday arithmetic shortcut for any situation where percentages are involved, from classroom homework to boardroom financial reviews.

1. Pick the type of calculation you need: percent of a number, a ratio as a percent, or percent change.
2. Enter the two values the calculation requires.
3. Read the result instantly.
4. Swap in new numbers to run another quick calculation.

Percentages show up everywhere — discounts, tips, tax, grades, and growth rates — but the direction of the calculation is easy to mix up. This tool separates the three common questions so you always get the right one.

• Three modes: X% of Y, X is what % of Y, and percent change.
• Handles increases and decreases with the correct sign.
• Instant results as you type.
• Clear layout for tips, discounts, and growth rates.
• All math runs locally in your browser.

Three formulas cover most needs. X percent of Y: result = (X / 100) × Y. X is what percent of Y: result = (X / Y) × 100. Percent change from old to new: result = ((new − old) / old) × 100, where a positive value is an increase and a negative value is a decrease.