How to Calculate Percentage Increase and Decrease (With Examples)
2026-02-13
What is Percentage Change?
Percentage change measures how much a value has increased or decreased relative to its original value. It's one of the most useful calculations in everyday life — from shopping discounts to salary raises to investment returns.
The Formula
Percentage Change = ((New Value - Old Value) ÷ Old Value) × 100- If the result is positive, it's a percentage increase
- If the result is negative, it's a percentage decrease
Percentage Increase Examples
Example 1: Salary Raise
Your salary went from $50,000 to $55,000.
((55,000 - 50,000) ÷ 50,000) × 100 = (5,000 ÷ 50,000) × 100 = 10% increase
Example 2: Price Increase
Gas prices went from $3.50 to $4.20 per gallon.
((4.20 - 3.50) ÷ 3.50) × 100 = (0.70 ÷ 3.50) × 100 = 20% increase
Percentage Decrease Examples
Example 1: Sale Discount
A shirt's price dropped from $80 to $60.
((60 - 80) ÷ 80) × 100 = (-20 ÷ 80) × 100 = -25% (25% decrease)
Example 2: Weight Loss
Weight went from 200 lbs to 180 lbs.
((180 - 200) ÷ 200) × 100 = (-20 ÷ 200) × 100 = -10% (10% decrease)
Common Mistakes to Avoid
- Using the wrong base: Always divide by the original value, not the new value
- Confusing increase and decrease: A 50% increase followed by a 50% decrease does NOT return to the original value
- Forgetting absolute values: The percentage change formula naturally produces negative numbers for decreases
Quick Reference
- 10% increase means the new value is 1.1× the original
- 25% decrease means the new value is 0.75× the original
- 100% increase means the value doubled
- 50% decrease means the value halved
Calculate It Instantly
Use our free Percentage Calculator to calculate percentage change between any two values. Select the "% Change" tab, enter your values, and get instant results.