Percent Calculator: Convert, Change, Increase and Fraction
Percent Calculator: Convert, Change and Increase
Five free calculators in one: percent to decimal, percent to fraction, percentage change, percentage increase, and percentage of a number.
Percent to Decimal Converter
%
Decimal Result
Percent to Fraction Converter
%
Simplified Fraction
Percentage Change Calculator
Percentage Change
Percentage Increase Calculator
Percentage Increase / Decrease
Percent of a Number
%
Result
Common Percent Conversion Reference Table
Percent (%)
Decimal
Fraction
Simplified
1%
0.01
1/100
1/100
5%
0.05
5/100
1/20
10%
0.10
10/100
1/10
12.5%
0.125
12.5/100
1/8
20%
0.20
20/100
1/5
25%
0.25
25/100
1/4
33.33%
0.3333
33.33/100
1/3
40%
0.40
40/100
2/5
50%
0.50
50/100
1/2
60%
0.60
60/100
3/5
66.67%
0.6667
66.67/100
2/3
75%
0.75
75/100
3/4
80%
0.80
80/100
4/5
90%
0.90
90/100
9/10
100%
1.00
100/100
1
150%
1.50
150/100
3/2
200%
2.00
200/100
2/1
How to Convert Percent to Decimal
Percent to decimal conversion is one of the most common math tasks in everyday life. The rule is simple: divide the percentage by 100 and drop the percent sign.
Decimal = Percentage ÷ 100
A faster shortcut is to move the decimal point two places to the left. So 37% becomes 0.37, and 8.5% becomes 0.085. This works because percent literally means “per 100.”
Worked Examples
Example 1
50% ÷ 100 = 0.50
Example 2
3.25% ÷ 100 = 0.0325
Example 3
125% ÷ 100 = 1.25
Example 4
0.5% ÷ 100 = 0.005
How to Convert Percent to Fraction
Percent to fraction conversion starts by writing the percent value over 100. Then you simplify the fraction by dividing the numerator and denominator by their greatest common divisor (GCD).
Fraction = Percentage / 100 → Simplify by GCD
For decimal percentages like 12.5%, first multiply both top and bottom by 10 to remove the decimal, giving 125/1000, then simplify to 1/8.
Worked Examples
25%
25/100 = 1/4
40%
40/100 = 2/5
12.5%
125/1000 = 1/8
66.67%
≈ 2/3
How to Calculate Percentage Change
Percentage change measures how much a value has increased or decreased relative to the original value. A positive result means an increase and a negative result means a decrease.
% Change = ((V2 − V1) / |V1|) × 100
V1 is the old or original value. V2 is the new or final value. The absolute value of V1 in the denominator is important when dealing with negative numbers, because it ensures the direction of change is captured correctly.
Percentage Change vs Percentage Difference
Percentage change is used when you have a clear old and new value, for example a price going from $40 to $50. Percentage difference is used when comparing two values without a clear before and after direction.
Increase
100 to 150: +50% change
Decrease
200 to 150: −25% change
Negative start
−25 to 25: +200% change
No change
80 to 80: 0% change
How to Calculate Percentage Increase
Percentage increase calculation tells you how much a value has grown as a share of the starting amount. It is always used when the final value is greater than the original value.
For example, if a product price rises from $80 to $100, the percentage increase is ((100 − 80) / 80) × 100 = 25%. To find the new value after a known percentage increase, multiply the original by (1 + rate). So 80 × 1.25 = 100.
Percentage Increase vs Percentage Decrease
Use percentage increase when the final value is higher. Use percentage decrease when the final value is lower. The formula is identical; the sign tells you the direction. A result above zero is an increase and a result below zero is a decrease.
Salary
$50k to $60k = +20% increase
Price drop
$200 to $150 = −25% decrease
Population
1000 to 1300 = +30% increase
Stock
$45 to $36 = −20% decrease
Frequently Asked Questions
How do I convert a percent to a decimal?
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To convert a percent to a decimal, divide the percentage number by 100 and remove the percent sign. For example, 75% divided by 100 equals 0.75. A quick shortcut is to move the decimal point two places to the left, so 75% becomes 0.75 and 3.5% becomes 0.035.
How do I convert a percent to a fraction?
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To convert a percent to a fraction, place the percentage number over 100 and then simplify. For example, 25% equals 25/100. Divide both numbers by their greatest common divisor, which is 25, to get 1/4. For decimal percentages like 12.5%, first multiply top and bottom by 10 to get 125/1000, then simplify to 1/8.
What is the formula for percentage change?
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Percentage change equals the new value minus the old value, divided by the absolute value of the old value, all multiplied by 100. The formula is: ((V2 minus V1) divided by the absolute value of V1) times 100. A positive result means an increase and a negative result means a decrease.
What is the difference between percentage change and percentage increase?
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Percentage increase only applies when the new value is greater than the original value and always produces a positive number. Percentage change can be either positive or negative depending on whether the new value is higher or lower than the old value. Both use the same formula but percentage increase is a specific case of percentage change.
How do I calculate percentage increase?
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To calculate percentage increase, subtract the starting value from the final value, divide that result by the starting value, then multiply by 100. For example, going from 50 to 75: 75 minus 50 equals 25, then 25 divided by 50 equals 0.5, then 0.5 times 100 equals a 50% increase.
What does percent mean in math?
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Percent means “per hundred” or “out of 100.” The word comes from the Latin phrase “per centum.” When you say 40%, you mean 40 out of every 100 units. It is a way to express a ratio or fraction with a denominator of 100, which makes comparisons between different quantities much easier.
How do I find what percent one number is of another?
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To find 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 120: 30 divided by 120 equals 0.25, then 0.25 times 100 equals 25%. So 30 is 25% of 120.
Why does percentage change use the absolute value of V1?
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The absolute value of V1 is used in the denominator to ensure the sign of the result correctly reflects the direction of change when the starting value is negative. Without it, a change from negative to positive could give a misleading result. For example, going from negative 25 to positive 25 is a 200% increase, which only works correctly when dividing by the absolute value of 25.
