Online Percentage Calculator

What is the Percentage Calculator?

The Percentage Calculator answers the three questions people actually ask: what is X percent of Y, X is what percent of Y, and what is the percentage change from X to Y. Type the numbers, get the answer instantly, and see the formula used so you can do it by hand next time. It also handles increase and decrease by a percentage (add 15 percent tax, take 20 percent off) and reverse percentages (a price after 20 percent off was 80; what was it before?). It runs in your browser.

How to use it

1. Pick the question type from the tabs.
2. Enter the two numbers.
3. Read the result and the formula. Copy if needed.

The three formulas

• X percent of Y: Y × X ÷ 100. 15 percent of 240 is 36.
• X is what percent of Y: X ÷ Y × 100. 36 is 15 percent of 240.
• Percentage change: (new − old) ÷ old × 100. From 240 to 276 is a 15 percent increase; from 276 back to 240 is a 13 percent decrease, because the base changed.

That last point is where most mistakes come from, along with confusing percentage points with percent (a rate going from 4 percent to 6 percent is up two points, or 50 percent). The mental shortcuts (10 percent then halve, swap the numbers: 8 percent of 25 equals 25 percent of 8) and the traps are in how to calculate percentages: the three questions, the shortcuts and the traps.

Everyday uses

• Discounts and sales tax.
• Tips and service charges.
• Exam scores and grade boundaries.
• Growth rates in reports and analytics.
• Interest and fees.

Related tools

Apply a percentage fee with the PayPal Fee Calculator, work with fractions instead with the Fraction Calculator, or do longer sums in the Scientific Calculator.

Frequently asked questions

How do I reverse a percentage?

Divide by (1 plus or minus the rate). A price of 80 after 20 percent off was 80 ÷ 0.8 = 100.

What is the difference between percent and percentage points?

Points are the simple difference between two percentages; percent change is relative to the starting value.

Does it round?

Results show two decimal places; the full value is used internally.