How to Calculate Percentage Increase & Decrease [Quick Guide]

Knowing how to calculate percentage increase and decrease is very useful. You can use it in everyday life, business, and school. It helps you see growth, losses, and discounts clearly.

What is Percentage Increase?

Percentage increase shows how much a value goes up. The formula is:$$\text{Percentage Increase} = \frac{\text{New Value – Original Value}}{\text{Original Value}} \times 100$$Percentage Increase=Original ValueNew Value – Original Value​×100

Example:

A product costs $50. It rises to $60.

1. Subtract: 60 − 50 = 10
2. Divide by original: 10 ÷ 50 = 0.2
3. Multiply by 100: 0.2 × 100 = 20%

The price went up by 20%.

What is Percentage Decrease?

Percentage decrease shows how much a value goes down. The formula is:$$\text{Percentage Decrease} = \frac{\text{Original Value – New Value}}{\text{Original Value}} \times 100$$Percentage Decrease=Original ValueOriginal Value – New Value​×100

Example:

A product costs $80. It drops to $60.

1. Subtract: 80 − 60 = 20
2. Divide by original: 20 ÷ 80 = 0.25
3. Multiply by 100: 0.25 × 100 = 25%

The price went down by 25%.

Steps to Calculate

1. Find the original and new values.
2. Subtract the numbers. Use the correct order.
3. Divide by the original value.
4. Multiply by 100.
5. Say if it is increase or decrease.

Real-Life Uses

• Finance: Track profit and loss.
• Shopping: Find discount savings.
• School: See grade changes.
• Research: Compare data.

Tips

• Always know which is the original value.
• Use parentheses for clarity.
• Increase and decrease are not equal.

Example:

Original = $100
50% increase → $150
50% decrease → $75

Final value is $75, not $100.

Common Mistakes

• Mixing original and new values.
• Forgetting to multiply by 100.
• Thinking increase and decrease cancel each other.

Conclusion

Percentage increase and decrease are easy to learn. Use the right formula and steps. Check your values carefully. Practice often. This skill helps in shopping, school, and business. You can see growth and losses quickly and clearly.

FAQs

Q1: How to calculate increase fast?

A: Subtract, divide by original, multiply by 100.

Q2: Can decrease be negative?

A: No. It is always positive.

Q3: What if original is zero?

A: You cannot calculate. Division by zero is impossible.

Q4: How in Excel?

A: Use =(New-Original)/Original*100.

Q5: Do increase and decrease cancel?

A: No. Base values matter.