Percentage Increase and Decrease Calculator
Move a number up or down by a percentage and see both results at once.
Method
How it works
The entered percentage is converted into an amount by multiplying it by the starting value. That amount is added for the increased result and subtracted for the decreased result.
The spread is the distance between those two results, equal to twice the change amount. Negative starting values or percentages follow the same arithmetic and may reverse the intuitive direction.
Common questions
Frequently asked questions
How do I increase a number by a percentage?
Multiply the value by the percentage divided by 100, then add that amount to the original value.
How do I decrease a number by a percentage?
Calculate the percentage amount from the original value and subtract it.
Why does increasing and then decreasing by the same percentage not return to the start?
This calculator shows both changes from the same original base. Sequential changes would use different bases.
Not financial advice. This calculator is for general informational purposes only. Check figures independently before making financial decisions.