Percentage Calculator
Calculate percentages, percentage change, increase, decrease, and proportions with interactive 100-square grid, donut gauge, and step-by-step methods.
1. Percentage of a Value
Formula: (P ÷ 100) × Value20% of 150 is 30
2. Value to Percentage (Proportion)
Formula: (Part ÷ Total) × 100%Finds the percentage fraction or proportion of one number compared to another (e.g. test scores, parts of a whole).
30 is 20% of 150
3. Percentage Change (Increase / Decrease)
Formula: ((New - Old) ÷ Old) × 100%Measures relative percentage growth, price inflation, discount rate, or percentage reduction between two values.
The change from 100 to 120 is a 20% increase
20 shaded / 80 empty
20% of 150 = 150% of 20
= 30
X% of Y is always equal to Y% of X. Reverse the numbers for easier mental calculation!
20% expressed in standard mathematical notations.
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Frequently Asked Questions
To find the percentage of a number, multiply the number by the percentage fraction (P / 100). For example, to find 20% of 150: 150 × (20 / 100) = 150 × 0.20 = 30.
Divide the part (numerator) by the total (denominator) and multiply by 100. For example, to find what percentage 30 is of 150: (30 / 150) × 100 = 0.20 × 100 = 20%.
Subtract the initial value from the final value, divide by the initial value, and multiply by 100: ((Final - Initial) / Initial) × 100. For example, increasing from 100 to 120 gives ((120 - 100) / 100) × 100 = +20% increase.
Divide the given part by the percentage in decimal form: Part / (P / 100). For example, if 30 is 20% of a number, the base is 30 / 0.20 = 150.
A famous commutative property of percentages states that X% of Y is always equal to Y% of X. For example, calculating 8% of 50 is the exact same as calculating 50% of 8, which is instantly 4.
The 100-square grid represents 100% as a 10×10 visual matrix. Shaded squares visually illustrate the exact proportion of the percentage relative to the whole, making fractional relationships immediately intuitive.
To add a percentage markup, multiply the base by (1 + P / 100). To subtract a discount, multiply the base by (1 - P / 100). For instance, an 8% tax on $50 equals $50 × 1.08 = $54.
Yes, 100%. All percentage calculations execute directly in your browser without transmitting any data over the network, ensuring complete privacy and seamless offline functionality via service workers.