Percentage Decrease Calculator
This calculator uses standard published formulas and is reviewed for calculation accuracy and clarity. The result is exact arithmetic, not an estimate.
Percentage decrease measures how much a value has fallen, expressed as a percentage of where it started. This calculator finds the percent decrease from an original value to a new, lower value. Enter the old and new values to see the drop — the examples below also show how to work forward to the value that remains after a given decrease.
How It Works
Subtract the new value from the old value to find the absolute drop, divide by the original value, and multiply by 100. The result is positive for a genuine decrease, and the old value is always the reference point. If the new value is higher than the old, you have an increase instead; use the Percentage Increase Calculator.
To find the value that remains after a decrease, multiply the original by (1 − rate ÷ 100). A 25% decrease on $80 leaves $80 × 0.75 = $60.
Worked Examples
Example 1 — a markdown. An item marked down from $80 to $60. ((80 − 60) ÷ 80) × 100 = 25% decrease.
Example 2 — falling traffic. Visits fell from 10,000 to 7,500. ((10,000 − 7,500) ÷ 10,000) × 100 = 25% decrease.
Example 3 — working forward. A $250 budget line is cut by 12%. Remaining = $250 × 0.88 = $220, a $30 reduction.
What This Result Means
The result is the fall as a share of the starting value. A 50% decrease halves the value; a 100% decrease takes it to zero. Note that a decrease and the increase needed to reverse it are not equal — a 50% drop requires a 100% rise to recover — so do not assume you can undo a percentage decrease with the same percentage increase.
When to Use This Calculator
Use it for price drops and markdowns, declines in sales or traffic, budget cuts, population decreases, or any figure that fell from a prior baseline and you want to express the drop as a percentage.
Limitations
- Requires a non-zero old value as the reference.
- A decrease cannot exceed 100%; at 100% the value has reached zero, and it cannot fall further as a percentage of the original.
- Only for declines; if the value rose, use the Percentage Increase Calculator.
- For a single tool that handles both directions with a sign, use the Percent Change Calculator.
Frequently Asked Questions
Is a 50% decrease the same as halving?
Yes. A 50% decrease reduces the value to half of the original.
Can you have more than a 100% decrease?
No. A 100% decrease means the value reached zero. A value cannot decrease by more than 100% of itself, because that would take it below zero.
What is the value after a percentage decrease?
Multiply the original by (1 − rate ÷ 100). For example, $80 decreased by 25% is $80 × 0.75 = $60.
Does a 25% decrease then a 25% increase return to the start?
No. $100 down 25% is $75; up 25% from $75 is $93.75 — below the start. Percentage changes apply to different bases, so they do not cancel.
How is this different from a discount?
The math is identical. A discount is simply a percentage decrease applied to a price — the Discount Calculator adds the dollar-savings and sale-price framing on top of the same formula.