Percentage Calculator
The percentage calculator allows you to find out what the amount, the percentage, the percent amount, the percent increase or the percent decrease is, if you know any of the two.
Instructions
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Explanations
Understanding Percentages
A percentage is a way to describe a number as a part of 100. The word percent means "per hundred," so 25% means 25 out of 100, or 25 divided by 100.
Percentages are useful because they make comparisons easier. Instead of comparing raw numbers directly, you can compare each value against the same base of 100. This is why percentages are common in discounts, taxes, interest rates, test scores, growth rates, financial changes, and everyday measurements.
This Percentage Calculator can help you find the percentage, the original amount, the percentage amount, an increased amount, or a decreased amount when enough related values are known.
Common percentage uses include:
- Finding a discount or sale price
- Calculating tips, tax, or commission
- Measuring increases and decreases
- Comparing two quantities on the same scale
- Understanding rates, scores, and proportions
About
Percentage Calculator
Version: 0.2
Author: Nicholas Tsakiris Alston
Frequently Asked Questions
What does percent mean?
Percent means per hundred. For example, 40% means 40 out of 100, or 0.40 as a decimal.
How do I find a percentage of a number?
Multiply the number by the percentage, then divide by 100. For example, 15% of 200 is 200 * 15 / 100 = 30.
How do I calculate a percentage increase?
Find the percentage amount and add it to the original number. For example, increasing 80 by 10% gives 80 + 8 = 88.
How do I calculate a percentage decrease?
Find the percentage amount and subtract it from the original number. For example, decreasing 80 by 10% gives 80 - 8 = 72.
How do I find the percentage change between two values?
Subtract the old value from the new value, divide by the old value, and multiply by 100. A positive answer is an increase, and a negative answer is a decrease.
Is percentage the same as decimal form?
They represent the same value in different forms. To convert a percentage to a decimal, divide by 100. For example, 25% equals 0.25.
Percentage Formulas
Percentage Formulas
What is P% of A?
Result = A * P / 100
Use this formula when you know the original amount and the percentage you want to apply.
A is what percent of B?
Percentage = A / B * 100
Use this formula when you want to compare one value to another as a percentage.
Increase a number by P%
Increased Amount = A + (A * P / 100)
This is the original amount plus the percentage amount.
Decrease a number by P%
Decreased Amount = A - (A * P / 100)
This is the original amount minus the percentage amount.
Percentage change between old and new values
Percentage Change = (New Value - Old Value) / Old Value * 100
A positive result is an increase. A negative result is a decrease.
Examples
Percentage Examples
What is 20% of 150?
150 * 20 / 100 = 30
20% of 150 is 30.
30 is what percent of 150?
30 / 150 * 100 = 20
30 is 20% of 150.
Increase 150 by 20%
150 + (150 * 20 / 100) = 180
150 increased by 20% is 180.
Decrease 150 by 20%
150 - (150 * 20 / 100) = 120
150 decreased by 20% is 120.
Percentage change from 150 to 180
(180 - 150) / 150 * 100 = 20
The value increased by 20%.