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Simple Calculators

Percentage Calculator

Solve any percentage problem — find percentages, calculate change, and apply increases or decreases

Find a percentage of a number

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Quick summary

A percentage calculator solves the four most common percentage problems: finding a percentage of a number (20% of 150 = 30), working out what percent one value is of another (30 is 25% of 120), calculating the percentage change between two values (80 to 100 is +25%), and increasing or decreasing a number by a percentage (200 plus 15% = 230).

Reviewed by Simple Calculators TeamLast reviewed

How to use this calculator

  1. Open the Calculation Type menu and pick the question you want answered: "What is X% of Y?", "X is what % of Y?", "Percentage change from X to Y", or "Increase/decrease X by Y%".
  2. Enter the first value. Its label changes with the mode — for example Percentage, Value, Original value, or Starting value.
  3. Enter the second value in the next field — the Number, Total, New value, or Percentage, depending on the mode you chose.
  4. Press Calculate (results also refresh as you type).
  5. Read the Result beside the form, then check the related calculations under it — such as the remaining amount, the inverse percentage, the absolute change, or the decreased value — to answer follow-up questions without re-entering numbers.

Percentage Formulas & Examples

Percentage of a Number

Result=P100×N\text{Result} = \frac{P}{100} \times N
P
Percentage (e.g. 20)
N
The number to take the percentage of

Worked example

What is 20% of 150?

Given
P = 20
N = 150
Calculation
Result=20100×150\text{Result} = \frac{20}{100} \times 150
Result
Result = 30

Percentage Change

% Change=New−Old∣Old∣×100\%\text{ Change} = \frac{\text{New} - \text{Old}}{|\text{Old}|} \times 100
New
The new value
Old
The original value

Worked example

Percentage change from 80 to 100

Given
Old = 80
New = 100
Calculation
% Change=100−80∣80∣×100\%\text{ Change} = \frac{100 - 80}{|80|} \times 100
Result
% Change = +25%

What Percent is X of Y?

%=XY×100\% = \frac{X}{Y} \times 100
X
The part value
Y
The whole value

Worked example

30 is what percent of 120?

Given
X = 30
Y = 120
Calculation
%=30120×100\% = \frac{30}{120} \times 100
Result
% = 25%

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For example, 15% of 200 = (15 ÷ 100) × 200 = 30, and 20% of 150 = 0.20 × 150 = 30. In the calculator, choose "What is X% of Y?", enter the percentage first and the number second. It also shows what is left over (150 − 30 = 120 in the second example).

How do I calculate percentage increase or decrease between two numbers?

Subtract the original value from the new value, divide by the absolute value of the original, and multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 × 100 = +25%; going from 50 to 40 is (40 − 50) ÷ 50 × 100 = −20%. A positive result is an increase and a negative result is a decrease.

How do I find what percent one number is of another?

Divide the part by the whole and multiply by 100. For example, 30 is (30 ÷ 120) × 100 = 25% of 120. Choose "X is what % of Y?", enter the part as the Value and the whole as the Total. The calculator also shows the inverse (120 is 400% of 30) and the remaining percentage (75%).

How do I increase or decrease a number by a percentage?

Multiply the number by (1 + percentage ÷ 100) to increase it. For example, 200 increased by 15% is 200 × 1.15 = 230. To decrease instead, multiply by (1 − percentage ÷ 100): 200 decreased by 15% is 170. The "Increase/decrease X by Y%" mode shows both results, plus the amount of change (30).

What is the difference between percentage change and percentage difference?

Percentage change has a direction and uses the original value as its base, so 80 to 100 is +25% while 100 to 80 is −20%. Percentage difference has no direction and divides the gap by the average of the two values. This calculator computes percentage change, which is what most price, salary, and growth questions need.

Why does a 50% decrease followed by a 50% increase not get me back to the start?

Because each percentage is taken from a different base. 100 decreased by 50% is 50, and 50 increased by 50% is only 75. To undo a decrease of p%, you need an increase of p ÷ (100 − p) × 100 percent — a 50% drop needs a 100% rise to recover.

Why can't I calculate percentage change from zero?

Percentage change divides by the original value, and dividing by zero is undefined, so the calculator asks for a nonzero original value. Going from 0 to any number is an infinite relative increase. In that case, describe the absolute change instead (for example, "up 25 units"), or pick a nonzero starting point.

Key terms

Percentage
A ratio expressed as a fraction of 100, denoted by the symbol %.
Percentage Change
The relative change between an old and new value, expressed as a percentage of the original.
Base Value
The original or reference value used when computing a percentage.

Methodology, sources & limitations

This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.

For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.