Percentage Calculator
Calculate X% of a number, find what percent one value is of another, reverse a percentage, compare percentage change, and work out percentage difference, discounts, increases, and decreases.
Select Scenario
Use this for questions like "what is 20% of 150?" to turn a percentage into a number.
Use this for shares, completion rates, ratios, and questions like "30 is what percent of 150?"
Use this for questions like “30 is 20% of what?” when you know the part and the percent but not the whole.
Compare an old value and a new value to see the relative increase or decrease.
Use this for markup, growth, tax, tips, or any value raised by a percentage.
Use this for discounts such as 20% off, price cuts, deductions, or values reduced by a percentage.
Use this when you know the final value after a percentage increase or decrease and need the original value.
Compare two values symmetrically using the average of both values as the baseline.
Result
30
Formula
20% of 150 = 30
percentage ÷ 100 × value
Result
13.3333%
Formula
20 is 13.3333% of 150
part ÷ whole × 100
Result
13.3333
Formula
20 is 150% of 13.3333
part ÷ percentage × 100
Result
650%
Formula
20 to 150 = 650% increase
(new value - original value) ÷ original value × 100
Change amount
130
Baseline
20
Result
180
Formula
150 plus 20% = 180
value × (1 + percentage ÷ 100)
Percentage amount
30
Result
120
Formula
150 minus 20% = 120
value × (1 - percentage ÷ 100)
Percentage amount
30
Reverse from
Result
-40
Formula
20 after 150% decrease started at -40
final value ÷ (1 - percentage ÷ 100)
Difference from original
60
Result
152.9412%
Formula
20 and 150 differ by 152.9412%
|first value - second value| ÷ average(|first value|, |second value|) × 100
Absolute difference
130
Average baseline
85
Common Scenarios
Basic
Change
Compare
Use this for questions like "what is 20% of 150?" to turn a percentage into a number.
Example
20% of 150 = 30.
Watch for
Use it when the percent and base value are known; the result is a number, not a percent.
Use this for shares, completion rates, ratios, and questions like "30 is what percent of 150?"
Example
30 out of 150 = 20%.
Watch for
Use it for shares, completion rates, and ratios; the second value is the whole.
Use this for questions like “30 is 20% of what?” when you know the part and the percent but not the whole.
Example
30 is 20% of 150.
Watch for
Use it when the whole is missing; the percentage cannot be 0.
Compare an old value and a new value to see the relative increase or decrease.
Example
100 to 125 = 25% increase.
Watch for
The original value is the baseline, so reversing the order changes the answer.
Use this for markup, growth, tax, tips, or any value raised by a percentage.
Example
150 plus 20% = 180.
Watch for
Use it for markup, tax, tips, or growth; the result is the final value after the increase.
Use this for discounts such as 20% off, price cuts, deductions, or values reduced by a percentage.
Example
150 minus 20% = 120.
Watch for
Use it for discounts, markdowns, or deductions; the result is the final value after the decrease.
Use this when you know the final value after a percentage increase or decrease and need the original value.
Example
80 after 20% off started at 100.
Watch for
Choose decrease for discounts and increase for growth; this mode works backward from the final value.
Compare two values symmetrically using the average of both values as the baseline.
Example
40 and 50 differ by 22.2222%.
Watch for
Use it when neither value is the original baseline; it uses the average of both values.
Quick Start
Common Scenarios
Use this for questions like "what is 20% of 150?" to turn a percentage into a number.
Use this for shares, completion rates, ratios, and questions like "30 is what percent of 150?"
Use this for questions like “30 is 20% of what?” when you know the part and the percent but not the whole.
Compare an old value and a new value to see the relative increase or decrease.
Use this for markup, growth, tax, tips, or any value raised by a percentage.
Use this for discounts such as 20% off, price cuts, deductions, or values reduced by a percentage.
Use this when you know the final value after a percentage increase or decrease and need the original value.
Compare two values symmetrically using the average of both values as the baseline.
Choose the Right Calculation
Read the Result Correctly
Usage Advice
Limitations & Compatibility
Privacy & Security
FAQ
Use percent of a value. For 20% of 150, the calculator computes 20 ÷ 100 × 150 = 30.
Use part as a percent of whole. Enter the part first and the whole second; 30 out of 150 is 20%.
Use find the whole. For “30 is 20% of what?”, the calculator computes 30 ÷ 20 × 100 = 150.
It uses the original value as the baseline: (new value - original value) ÷ original value × 100.
Use subtract percentage. For 20% off 150, the calculator returns 120 as the sale price.
Use reverse percentage, choose after decrease / discount, then enter the sale price and discount percent. For 80 after 20% off, the original price is 100.
Use percentage change when one value is clearly the original value. Use percentage difference when you only want the symmetric gap between two values.
Percentage points are the direct gap between two percentages. Percent change is relative to the starting value.
A ratio or percentage change needs a baseline. Dividing by 0 is undefined, so those modes block 0 as the whole or original value.
A 20% decrease turns 100 into 80. To return from 80 to 100, the increase is 25%, not 20%.
Because the second calculation uses a different base. 100 increased by 20% becomes 120, then decreasing 120 by 20% gives 96, not 100.