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Percentage Decrease Calculator

Calculate percentage decrease online — free, step by step. The drop in percent from two values, or the value after a percentage decrease.

Quick answer
How do you calculate a percentage decrease?
Percentage decrease is the drop divided by the old value, times 100: (old − new) ÷ old · 100. Example: from 250 to 200 that is (250 − 200) ÷ 250 · 100 = 20% decrease. To reduce a value by p%, compute value − value · p ÷ 100.
The tool

Enter values — get full working

By what percent does the value drop?
Comma or dot as decimal separator, negative values allowed.
Step-by-step
Press Calculate to see every step.
HowTo

Percentage Decrease Calculator — step-by-step

How do you calculate a percentage decrease?
  1. 1
    Step 1 of 4

    Choose values or a percentage

    Either you have two values (old and new) and want the decrease in percent, or you have a starting value and a decrease percentage and want the new value.

  2. 2
    Step 2 of 4

    Find the drop

    With two values: old − new. Example 250 − 200 = 50. When applying: value · p ÷ 100, e.g. 250 · 20 ÷ 100 = 50.

  3. 3
    Step 3 of 4

    Relate or subtract

    For the decrease in percent: 50 ÷ 250 = 0.2. For the new value: 250 − 50 = 200.

  4. 4
    Step 4 of 4

    State the result

    Decrease: 0.2 · 100 = 20%. Or new value: 200.

Examples

Percentage Decrease Calculator — examples

Worked examples with full working
250 → 200
(250 − 200) ÷ 250 · 100
20%
250 − 20%
250 − (250 · 20 ÷ 100)
= 250 − 50
200
80 → 60
(80 − 60) ÷ 80 · 100
25%
120 − 15%
120 − (120 · 15 ÷ 100)
102
1,000 → 750
(1000 − 750) ÷ 1000 · 100
25%
49 − 30%
49 − (49 · 30 ÷ 100)
34.3
Theory

What is a percentage decrease?

A percentage decrease describes by what share a value has shrunk, relative to the starting value. It is (old value − new value) ÷ old value · 100. Conversely, you reduce a value by p% by subtracting value · p ÷ 100 — or more compactly by multiplying by the factor (1 − p ÷ 100). So "minus 20%" equals multiplying by 0.8. Percentage decreases show up in discounts, depreciation, population decline and falling measurements.

Pitfalls

Common mistakes

Wrong reference value

The decrease is relative to the old value. From 250 to 200 is a 20% decrease, not 25%.

Subtracting twice ≠ double the percent

Two 10% decreases don't make 20%, because the second acts on the already reduced value (0.9 · 0.9 = 0.81 → 19%).

Confusing decrease and increase

A 50% decrease halves; a following 50% increase does not undo it.
FAQ

Frequently asked questions

Glossary

Glossary — key terms explained simply

Whole (base)
The reference value that equals 100%.
Part (value)
The amount that belongs to a percentage.
Rate
The percentage (per hundred).
Difference
The result of a subtraction (new − old).
Relative
Expressed against a reference, dimensionless.
Absolute
In the unit of the quantity, without reference.
Factor
Number you multiply by (e.g. 1.25 for +25%).
Percentage point
Absolute difference between two percentages.