What is percentage decrease?
Percentage decrease tells you how much a value has fallen compared with where it started, expressed as a share of the original. It is used for price drops, falling sales, weight loss, discounts and many other everyday comparisons.
Percentage decrease formula
percentage decrease = (original − new) ÷ original × 100
To find the value after a known decrease, use new value = original × (1 − percent ÷ 100).
Step-by-step example
A jacket costs 80 and is now 60.
| Step | Calculation | Result |
|---|---|---|
| 1. Find the drop | 80 − 60 | 20 |
| 2. Divide by the original | 20 ÷ 80 | 0.25 |
| 3. Convert to percent | 0.25 × 100 | 25% |
The price fell by 25%.
Common mistakes
- Dividing by the new value instead of the original value.
- Treating a decrease followed by the same percentage increase as a return to the start. A 20% drop needs a 25% rise to get back, which is what our backwards percentage calculator helps you work out.
- Mixing up percentage points and percent. Going from 10% to 8% is a drop of 2 percentage points but a 20% decrease.
How to use this calculator
- Enter your values. Find how much a number has dropped, as a percentage, or calculate the value after a decrease.
- Check units and assumptions. Make sure the inputs use the same scale and that any optional settings match your situation.
- Calculate and review. Compare the output with the formula below and note any limitations stated on the page.
Formula and calculation method
Use the relevant percentage relationship shown on this page. For a change between two values, compare the difference with the correct reference value; for reverse calculations, rearrange the equation to solve for the missing starting value.
Worked example
For example, if a price changes from $60 to $80, the difference is $20. Dividing $20 by the starting value of $60 and multiplying by 100 gives a 33.33% increase. Always use the original value as the denominator for percentage increase.
Search and practical tips
People commonly search for a percentage decrease calculator – free tool, how to calculate the result step by step, which formula to use, and how to check the answer manually. Use the formula above as a transparent starting point, and consult the relevant institution, agency, or qualified professional when an official rule or personal circumstances affect the result.
Frequently asked questions
What is the formula for percentage decrease?
Percentage decrease = (original − new) ÷ original × 100. For 80 falling to 60: (80 − 60) ÷ 80 × 100 = 25%.
What if the new value is higher than the original?
Then the change is an increase, not a decrease. The calculator shows the percentage increase instead.
Can a percentage decrease be more than 100%?
No. A value can fall by at most 100%, which brings it to zero. A bigger drop would mean a negative number.
How do I take a percentage off a price?
Switch to 'Find the value after a decrease', enter the price and the discount percent. A 15% discount on 200 gives 170.
Why can't the original value be zero?
The formula divides by the original value, and division by zero is undefined, so a percentage change from zero cannot be calculated.