how to calculate percent increase

Percent increase is one of the most practical math skills you can learn. You use it when prices go up, when your salary changes, when website traffic grows, and when investment values rise. Once you understand the formula, it becomes quick and intuitive.

What Is Percent Increase?

Percent increase tells you how much something grew compared to where it started. It compares the change to the original value, then expresses that relationship as a percentage.

This formula is useful because it scales the change relative to the starting point. A $20 increase means something different if you started at $40 versus $400.

Step-by-Step: How to Calculate Percent Increase

1) Find the change

Subtract the original number from the new number:

2) Divide by the original value

This gives you the growth as a decimal:

3) Multiply by 100

Convert the decimal to a percentage:

Example Calculations

Example 1: Simple increase

A product price goes from 50 to 65.

• Change = 65 − 50 = 15
• Decimal Growth = 15 ÷ 50 = 0.30
• Percent Increase = 0.30 × 100 = 30%

Example 2: Salary increase

Your salary rises from 48,000 to 52,800.

• Change = 52,800 − 48,000 = 4,800
• Decimal Growth = 4,800 ÷ 48,000 = 0.10
• Percent Increase = 0.10 × 100 = 10%

Example 3: A decrease instead of increase

If the new value is less than the original, your result is negative, which means a percent decrease.

• Original = 200, New = 150
• Change = 150 − 200 = −50
• Percent Change = (−50 ÷ 200) × 100 = −25%

So the value decreased by 25%.

Quick Reference Table

Original	New	Change	Percent Change
100	120	+20	+20%
80	100	+20	+25%
250	300	+50	+20%
90	72	−18	−20%

Common Mistakes to Avoid

• Dividing by the new value instead of the original value. Always divide by the starting point.
• Forgetting to multiply by 100. If you stop at 0.18, that is 18%, not 0.18%.
• Ignoring negative results. A negative percent indicates a decrease, not an error.
• Mixing units. Make sure both values represent the same unit (dollars, users, kilograms, etc.).

Percent Increase vs. Percentage Points

These are not the same thing:

• If an interest rate rises from 5% to 7%, that is a 2 percentage point increase.
• Relative to 5%, moving to 7% is a 40% increase in the rate itself.

Use percentage points when comparing percentages directly, and percent increase when comparing values relative to an original amount.

Special Cases

When the original value is 0

You cannot compute a traditional percent increase from zero because division by zero is undefined.

When values are negative

You can still apply the formula, but interpretation can be tricky depending on context (profit/loss, temperatures, debt values). In practical business and finance contexts, use domain-specific rules when negatives are involved.

Reverse Problem: Find the New Value from a Percent Increase

Sometimes you know the original number and the percent increase, and you need the final value.

Example: Original = 200, Increase = 15%

New Value = 200 × (1 + 0.15) = 200 × 1.15 = 230

Final Takeaway

To calculate percent increase, always remember this sequence: subtract, divide, multiply by 100. With that one pattern, you can quickly evaluate growth in prices, income, sales, traffic, and performance metrics.

If you want a fast answer, use the calculator above. If you want confidence, work through a few examples by hand until the formula becomes second nature.