Question 1

How do I calculate a percentage of a number?

Accepted Answer

To find X% of Y, multiply Y by (X divided by 100). For example, 20% of 150 = 150 × 0.20 = 30. Use the "Find Value" tab in our calculator — enter the percentage and base number, and the answer appears instantly.

Question 2

How do I calculate what percentage one number is of another?

Accepted Answer

Divide the part by the whole, then multiply by 100. For example, 30 is what percent of 200? (30 ÷ 200) × 100 = 15%. Use the "Find Percent" tab and enter the two numbers.

Question 3

How do I calculate percentage change (increase or decrease)?

Accepted Answer

Percentage change = ((New Value − Original Value) ÷ |Original Value|) × 100. If the result is positive, it's an increase; if negative, it's a decrease. For example, from 100 to 120: ((120 − 100) ÷ 100) × 100 = +20% increase. Use the "% Change" tab.

Question 4

How do I calculate a discount percentage?

Accepted Answer

To find the discounted price: use "Find Value" — enter the discount percent (e.g. 25) and the original price (e.g. 80). The result (20) is the discount amount; subtract from the original to get the sale price ($60). To find what percent off: use "Find Percent" — enter the discount amount as the part and the original price as the whole.

Question 5

How do I calculate a tip percentage?

Accepted Answer

Use the "Find Value" tab. Enter the tip percentage (e.g. 18 for 18%) and the bill total (e.g. 65). The result is the tip amount ($11.70). The quick preset buttons (15%, 20%, 25%) make common tip calculations one click away.

Question 6

What is the percentage formula?

Accepted Answer

There are four core percentage formulas: (1) Find Value: Result = (Percent ÷ 100) × Base. (2) Find Percent: Percent = (Part ÷ Whole) × 100. (3) Find Base: Base = Value ÷ (Percent ÷ 100). (4) Percent Change: Change% = ((New − Old) ÷ |Old|) × 100. Each formula is shown live as you type in our calculator.

Percentage Calculator