Percentage Calculator
Calculate percentages quickly: find X% of Y, percentage change, increase or decrease values.
Percentage Calculator
Calculate percentages quickly and easily
What is X% of Y?
15% of 200
30
Quick Reference: Percentages of 200
How to Use This Calculator
Choose your calculation type from the four options: find X% of Y, find what percent one number is of another, calculate percentage change, or increase/decrease a value by a percentage.
X% of Y answers questions like "What is 15% of 200?" - perfect for calculating tips, discounts, or portions.
X is ?% of Y answers "30 is what percent of 150?" - useful for understanding proportions and ratios.
% Change calculates the percentage difference between two values - great for tracking price changes, growth rates, or performance differences.
X ± Y% calculates what you get when you increase or decrease a value by a percentage - perfect for markups, discounts, or adjustments.
Quick Percentage Tricks
Finding 10%: Move the decimal point one place left. 10% of 250 = 25. 10% of 1,500 = 150.
Finding 5%: Find 10% and divide by 2. 5% of 200 = 10% (20) ÷ 2 = 10.
Finding 15%: Find 10% and add half of it. 15% of 80 = 10% (8) + 5% (4) = 12.
Finding 20%: Find 10% and double it. 20% of 150 = 10% (15) × 2 = 30.
Finding 25%: Divide by 4. 25% of 120 = 120 ÷ 4 = 30.
Frequently Asked Questions
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, to find what percent 30 is of 150: (30 ÷ 150) × 100 = 20%. So 30 is 20% of 150.
How do I find X% of a number?
Multiply the number by the percentage divided by 100. For example, 15% of 200: 200 × (15 ÷ 100) = 200 × 0.15 = 30. A quick trick: to find 10%, just move the decimal point one place left.
How do I calculate percentage change?
Use the formula: ((New Value - Old Value) ÷ Old Value) × 100. For example, if a price went from $100 to $125: ((125 - 100) ÷ 100) × 100 = 25% increase.
How do I increase a number by a percentage?
Multiply the number by (1 + percentage/100). For example, to increase 100 by 20%: 100 × 1.20 = 120. Or add the percentage of the number: 100 + (100 × 0.20) = 120.
How do I decrease a number by a percentage?
Multiply the number by (1 - percentage/100). For example, to decrease 100 by 20%: 100 × 0.80 = 80. Or subtract the percentage of the number: 100 - (100 × 0.20) = 80.
Why doesn't a 20% increase then 20% decrease give me the original number?
Because percentages are relative to the current value. If you start with 100, increase by 20% (to 120), then decrease by 20%, you get 120 × 0.80 = 96, not 100. The second percentage applies to the new value, not the original.
How do I convert a decimal to a percentage?
Multiply by 100. For example, 0.25 = 25%, 0.05 = 5%, 1.5 = 150%. To convert a percentage to a decimal, divide by 100: 25% = 0.25.
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