how do you calculate percentage growth

If you've ever asked, "How do you calculate percentage growth?", you're asking one of the most useful math questions in business, investing, budgeting, and everyday life. Percentage growth tells you how much something increased relative to where it started.

The core percentage growth formula

The standard formula is:

This gives a percentage that tells you how much growth happened compared to the original amount.

Quick example

• Old value: 80
• New value: 100
• Change: 100 − 80 = 20
• Growth rate: 20 / 80 = 0.25
• Percentage growth: 0.25 × 100 = 25%

So, going from 80 to 100 is a 25% increase.

Step-by-step method you can use every time

1) Subtract the old value from the new value

This gives you the absolute change.

2) Divide that change by the old value

This converts the change into a ratio relative to your starting point.

3) Multiply by 100

This turns the ratio into a percentage.

What if the result is negative?

If your calculation comes out negative, that means the value declined rather than grew.

That's a 25% decrease, not growth.

Common real-world uses

• Revenue growth: Compare this year vs. last year sales.
• Investment performance: Measure gain or loss on stocks, funds, or property.
• Population change: Track growth by city, country, or region.
• Website metrics: Measure traffic, email subscribers, or conversion growth.
• Salary progression: Calculate raise percentages over time.

Percentage growth vs. percentage points

People often confuse these. They are different:

• Percentage growth: Relative increase from an old value to a new value.
• Percentage points: The arithmetic difference between two percentages.

Example: If a rate moves from 10% to 12%, that's:

• +2 percentage points
• 20% growth in the rate itself (because 2 ÷ 10 = 0.20)

What if the old value is zero?

The basic formula divides by the old value, so when old value = 0, percentage growth is mathematically undefined. In practical terms, people often report the absolute change instead, or describe it as "growth from zero."

Our calculator flags this case so you don't accidentally report a misleading percentage.

How to calculate annualized growth (CAGR)

If growth happened over multiple years (or months), you might want a smoothed annual rate called CAGR (Compound Annual Growth Rate):

Example: An investment grows from 1,000 to 1,610 in 5 years.

• Ratio: 1,610 / 1,000 = 1.61
• 5th root: 1.61^(1/5) ≈ 1.10
• CAGR: (1.10 − 1) × 100 = 10% per year

Common mistakes to avoid

• Using the new value as the denominator (it should be the old value).
• Forgetting to multiply by 100 after dividing.
• Mixing units (for example, dollars vs. thousands of dollars).
• Confusing a one-time growth rate with annualized growth.

Final takeaway

To calculate percentage growth, use this simple structure:

That's it. Once you know this formula, you can evaluate growth in finance, business, school, or personal goals with confidence. Use the calculator above whenever you want a quick answer, plus optional annualized growth for multi-period data.