Free Online Percentage Calculator
Calculate percentages — find X% of Y, what percent X is of Y, or percentage change
Result
30
Formula
(15 / 100) × 200 = 30
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About this tool
Calculate percentages instantly with this free online percentage calculator. Whether you need to find what a percentage of a number is, determine what percent one number is of another, or calculate the percentage change between two values, this tool gives you the answer in real time as you type. The calculator supports three modes: find X% of Y (useful for tips, discounts, and tax calculations), find what percentage X is of Y (useful for test scores, statistics, and proportions), and calculate percentage change from one value to another (useful for price changes, growth rates, and financial analysis). Each result is shown alongside the formula used, so you can verify the math or learn how to calculate percentages by hand. All calculations happen in your browser — no data is sent to any server. Whether you are a student checking homework, a shopper calculating a discount, or a professional doing quick financial math, this tool delivers instant, accurate results.
Frequently Asked Questions
Divide the part by the whole and multiply by 100. For example, to find what percent 30 is of 200: (30 / 200) × 100 = 15%. Use the "X is what %" mode in the calculator above for instant results.
Percentage change = ((New Value - Old Value) / Old Value) × 100. A positive result means an increase, a negative result means a decrease. For example, going from 200 to 250 is a 25% increase.
Percentage change measures the relative change from an original value to a new value and has a direction (increase or decrease). Percentage difference compares two values without a defined starting point, using the average as the base.
Divide the percentage by 100. For example, 25% becomes 0.25, and 7.5% becomes 0.075. To convert back, multiply the decimal by 100.
Subtract the old value from the new value, divide by the old value, and multiply by 100. For example, from 80 to 100: ((100 - 80) / 80) × 100 = 25% increase.
Use the "X is what %" mode. Enter the discount amount as the value and the original price as the total. For example, a $30 discount on a $200 item: (30 / 200) × 100 = 15% discount.
Yes. A percentage greater than 100 means the value exceeds the reference amount. For example, if sales grew from 100 to 250, that is a 150% increase. A value of 300% of X means three times X.
Divide the result by the percentage and multiply by 100. For example, if 30 is 15% of the original number: 30 / 15 × 100 = 200. The original number is 200.
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