Percent of total
Use part ÷ whole × 100 to measure how much of the whole a part represents.
061 · UNIT & CALCULATOR
Percentage & Percent Change Calculator
Calculate percentages, increases, decreases, and values after a percent change with clear formulas.
LOCALCALCULATE IN YOUR BROWSER
LOCALValues are calculated locally and are not sent to a server.
What is X% of Y?
Enter a percentage and a base value.
RESULT · Result
30
(20 ÷ 100) × 150 = 30
Advanced settings · Display precision
2
HOW TO USE
How to use
- 01
Choose the percentage question you want to answer.
- 02
Enter the two numbers required for the selected mode.
- 03
Check the result together with the formula using your actual values.
- 04
For percentage change, remember that the original value is the denominator.
- 05
Adjust precision or copy the result when needed.
PERCENT GUIDE
Start by identifying the percentage base
The same two numbers can produce different answers depending on the base, denominator, and percentage question.Value of a percent
Use base × percent ÷ 100 to calculate the actual amount represented by a percentage.
Percent change
Use (new − original) ÷ original × 100. The original value is the denominator.
Apply a percent
Increase with base × (1 + p/100) and decrease with base × (1 − p/100).
Reverse the change
Recover the original by dividing by the applied multiplier; a 100% decrease cannot be reversed.
Percentage points
A move from 20% to 25% is +5 percentage points but a +25% relative increase.
IMPORTANT NOTES
Important notes
- Percent increase and decrease use the original value as the denominator. 80→100 is +25%, while 100→80 is -20%.
- Percent change from an original value of zero is undefined and is not forced to 0%.
- Percentages above 100%, such as 150%, can be valid and are not blocked.
- Percent and percentage points are different concepts. This tool reports percent change.
- Reverse percentage after a 100% decrease is impossible because the divisor becomes zero.
FAQ
Frequently asked questions
01How much is the increase from 80 to 100?+
It is a 25% increase: (100-80) ÷ 80 × 100 = 25%.
02How much is the decrease from 100 to 80?+
It is a 20% decrease because 100 is the original denominator.
03Does +20% followed by -20% return to the start?+
No. 100 becomes 120 and then 96 because the second percentage uses a different base.
04What if the original value is zero?+
Standard percent change is undefined because it would divide by zero.
05Can I enter 150%?+
Yes. Percentages above 100% can be valid.