Percentage Change Calculator
Enter the original and new values to calculate the decrease automatically.
Percentage decrease formula
Subtract the new value from the original value, divide the decrease by the original value, and multiply by 100.
Example: decrease from 100 to 80
The decrease is 20. Divide 20 by 100 to get 0.20, so the percentage decrease is 20%.
Example: decrease from 50 to 40
The decrease is 10. Divide 10 by the original 50 to get 0.20, or a 20% decrease.
Why the denominator is the original value
The percentage describes the loss relative to where the value started. Using the ending value changes the comparison.
Percentage decrease vs. percentage points
If a rate falls from 30% to 24%, that is a drop of 6 percentage points. Relative to 30%, it is a 20% decrease.
What if the original value is zero?
A standard percentage decrease cannot be calculated from zero because the formula divides by the original value.
Excel and Google Sheets formula
Format the result as a percentage.
Related percentage tools
See how to calculate percentage increase, use the discount calculator for sale prices, or compare peer values with the percent difference calculator.
Frequently asked questions
Is a 20% decrease followed by a 20% increase back to the starting value?
No. The second percentage is applied to a different base.