how to calculate percentage increase

What is percentage increase?

Percentage increase tells you how much a value has gone up compared to where it started. It’s one of the most useful math tools in everyday life because it shows relative change, not just raw difference.

For example, a $10 increase can be huge if something originally cost $20, but small if it originally cost $1,000. Percentage increase helps you compare those situations fairly.

The percentage increase formula

There are three simple parts to the formula:

• Find the change: New Value - Original Value
• Divide the change by the original value
• Multiply by 100 to convert to a percentage

Step-by-step: how to calculate percentage increase

Step 1: Identify your two numbers

Start with the original value (the old number), then the new value (the updated number).

Step 2: Subtract to get the difference

Difference = New Value - Original Value.

Step 3: Divide by the original value

This gives you the growth as a decimal relative to where you started.

Step 4: Multiply by 100

Now convert the decimal to a percent.

Example calculations

Example 1: Price increase

A gym membership goes from $40 to $50.

• Difference: 50 - 40 = 10
• Divide by original: 10 / 40 = 0.25
• Convert to percent: 0.25 × 100 = 25%

The membership price increased by 25%.

Example 2: Salary increase

Your salary goes from $60,000 to $66,000.

• Difference: 66,000 - 60,000 = 6,000
• Divide by original: 6,000 / 60,000 = 0.10
• Convert to percent: 0.10 × 100 = 10%

Your salary increased by 10%.

Example 3: Website traffic increase

Monthly visitors rise from 12,500 to 18,000.

• Difference: 18,000 - 12,500 = 5,500
• Divide by original: 5,500 / 12,500 = 0.44
• Convert to percent: 0.44 × 100 = 44%

Traffic increased by 44%.

Percentage increase vs. percentage points

This is a common source of confusion.

• Percentage increase compares relative growth.
• Percentage points are simple subtraction between two percentage values.

If an interest rate moves from 5% to 7%:

• It increased by 2 percentage points.
• It also increased by 40% relative to 5%.

Common mistakes to avoid

• Using the new value as the denominator: always divide by the original value.
• Forgetting to multiply by 100: 0.2 means 20%.
• Mixing units: compare dollars with dollars, not dollars with cents unless converted first.
• Ignoring negative results: if your answer is negative, that means it’s a percentage decrease.

What if the original value is zero?

If the original value is 0, percentage increase is mathematically undefined because division by zero is not possible. In practical terms, you can report it as “not defined” or describe the change in absolute terms instead.

Quick mental math trick

When the increase is a known fraction of the original value, you can estimate quickly:

• Increase is 1/10 of original → about 10%
• Increase is 1/4 of original → about 25%
• Increase is 1/2 of original → about 50%
• Increase equals original value → 100%

Why this matters in real life

Knowing how to find percent change helps you make better decisions in finance, business, investing, health, and productivity. Whether you are comparing expenses, evaluating growth, or tracking progress toward goals, percentage increase gives context that raw numbers cannot.

Final takeaway

To calculate percentage increase, subtract old from new, divide by old, and multiply by 100. That’s it. Use the calculator above for instant results, and you’ll never have to guess again when comparing growth.