To calculate percentage decrease, subtract the new value from the original, divide by the original, then multiply by 100. For example, going from 80 to 60 is a 25% decrease because ((80 − 60) ÷ 80) × 100 = 25.
This guide walks through the formula with three worked examples, covers the difference between decrease and change, and links to a free calculator so you can skip the manual math.
The Percentage Decrease Formula
Three steps:
- Subtract: Original value − New value = the drop.
- Divide: Drop ÷ Original value = the decimal change.
- Multiply: Decimal change × 100 = the percentage.
The result is always a positive number — even though the value went down. This is different from percentage change, which uses a negative sign to indicate a decrease.
Example 1: A Price Cut
A jacket was $120 and is now on sale for $84. What's the percentage decrease?
Example 2: Falling Website Traffic
Your site had 12,000 visits last month and 9,600 this month. What's the drop?
Example 3: Stock Price Drop
A stock fell from $45.50 to $36.40. What percentage did it lose?
Percentage Decrease vs. Percentage Change
These two terms are often confused. Here's the difference:
- Percentage change uses the same formula but produces a signed result: +30% for an increase, −30% for a decrease. It's a general-purpose term.
- Percentage decrease always produces a positive number. You mention "decrease" to signal the direction.
So "20% decrease" and "−20% change" mean the same thing, but you'd never say "−20% decrease" — that's a double negative.
Common Mistakes to Avoid
- Dividing by the new value instead of the original. Always use the original as the base. This is the #1 mistake in percentage decrease problems.
- Reported as negative when it should be positive. If you say "a −25% decrease," that actually means a 25% increase. Use positive numbers for decreases.
- Confusing the discount with the final price. "30% off" means the new price is 70% of the original, not 30% of it.
- Assuming decreases are symmetric with increases. A 50% decrease requires a 100% increase to get back to the start. A 20% decrease requires a 25% increase to recover.
Recovery math: If a stock drops 50%, it must gain 100% just to break even. This is why recovering from losses is harder than the original drop suggests — and why investors pay close attention to percentage decrease.
How to Find the Original Price (Reverse Percentage)
Shopping sales often hide the original price. Here's how to work backward:
Skip the Math — Use a Calculator
If you need to do percentage decrease calculations often — for discounts, price tracking, or reporting — our free percentage calculator handles it instantly. It also does percentage increase, X% of Y, and other common percent problems.
📊 Free Percentage Calculator
Calculate percentage decrease, increase, and more — instantly, in your browser.
Open Percentage Calculator →Frequently Asked Questions
Can percentage decrease be more than 100%?
No. A 100% decrease means the value dropped to zero. A decrease above 100% would require the value to go negative, which isn't meaningful for prices, populations, or most real-world numbers.
How do I calculate a discount percentage?
Discount % = ((Original Price − Sale Price) ÷ Original Price) × 100. Example: $80 → $60 is ((80 − 60) ÷ 80) × 100 = 25% off.
What's the difference between percentage decrease and percentage point decrease?
Percentage decrease measures relative change. A percentage point decrease measures absolute change between two percentages. If a rate drops from 20% to 15%, that's a 5 percentage point drop — but a 25% relative decrease.
How do I calculate average percentage decrease over time?
Use the CAGR formula: ((End ÷ Start)^(1/n) − 1) × 100, where n is the number of periods. Never average percentages directly — that gives the wrong answer.
What does a 0% decrease mean?
It means the value didn't change. The original and new values are identical.