The Basic Formula for Percentage Increase

Percentage increase measures how much something has grown from its starting value, shown as a percentage. The formula is straightforward: subtract the original value from the new value, divide that difference by the original value, then multiply by 100.

Written as a formula, it looks like this:

Percentage Increase = ((New Value − Original Value) ÷ Original Value) × 100

The result tells you what fraction of the original amount the increase represents, expressed as a percentage. If you get 25%, that means the new value is 25% larger than the original. This same calculation works whether you are tracking a price change, a salary adjustment, a utility bill, or any other quantity that grows over time.

Key Takeaways

  • Percentage increase uses the formula ((New Value − Original Value) ÷ Original Value) × 100.
  • The original value always goes in the denominator, even if it is smaller than the new value.
  • A negative result means the value decreased, not increased.
  • Percentage increase and percentage change are the same calculation; the term "change" works for both increases and decreases.
  • You can perform this calculation on a basic calculator, spreadsheet, or by hand using pencil and paper.

Working Through a Real Example

Say your electric bill was $120 last month and $150 this month. To find the percentage increase:

First, find the difference: $150 − $120 = $30.

Next, divide that difference by the original value: $30 ÷ $120 = 0.25.

Finally, multiply by 100 to convert to a percentage: 0.25 × 100 = 25%.

Your electric bill increased by 25%. This means the new bill is 125% of the original bill (100% of the original plus the 25% increase). You can verify this makes sense: 25% of $120 is $30, and $120 + $30 = $150, which matches your new bill.

When the Result Is Negative

If your calculation gives you a negative percentage, the value actually decreased, not increased. This is still useful information—it tells you the direction and size of the change.

For example, if a product cost $80 last year and $60 this year, the calculation is ((60 − 80) ÷ 80) × 100 = (−20 ÷ 80) × 100 = −25%. The negative sign means the price fell by 25%, not rose.

In everyday language, you might call this a "25% decrease" rather than a "−25% increase," but mathematically they describe the same thing. The formula itself does not care whether the change is up or down—it straightforward reports what happened.

Using a Calculator or Spreadsheet

You can do this calculation on any basic calculator by entering the numbers in order. For repeated calculations or larger datasets, a spreadsheet like Excel or Google Sheets is faster and reduces the chance of typing errors.

In Excel or Google Sheets, the formula is entered as =(new value − original value)/original value*100. If your original value is in cell A1 and your new value is in cell B1, you would type =(B1−A1)/A1*100 and press Enter.

Spreadsheets are especially useful if you need to calculate percentage increase for dozens of items at once—you can enter the formula once and copy it down to all the rows that need it. This saves time and ensures every row uses the same calculation method.

Common Mistakes to Avoid

The most frequent error is dividing by the new value instead of the original value. Remember: the original (starting) value always goes in the denominator. This matters because it changes your answer significantly. If you accidentally divide by the new value, your percentage will be too small.

Another mistake is forgetting to multiply by 100 at the end. If you stop after dividing, you get a decimal (like 0.25) instead of a percentage (25%). The multiplication by 100 shifts the decimal point two places to the right and converts your answer into the percentage form people expect to see.

A third pitfall is using the wrong starting point. Make sure you know what "original" means in your situation. If you are comparing this month to last month, last month is original. If you are comparing this year to five years ago, five years ago is original. Picking the wrong baseline will give you a meaningless result.

Percentage Increase vs. Percentage Point Increase

These two terms sound similar but mean different things. Percentage increase is what you calculate with the formula above—it shows growth relative to the starting value.

Percentage point increase is simpler: it is just the difference between two percentages. If unemployment was 5% last year and 7% this year, that is a 2 percentage point increase. But the percentage increase in unemployment is ((7 − 5) ÷ 5) × 100 = 40%.

News reports sometimes mix these up, which can make a change sound bigger or smaller than it is. When you see a percentage mentioned, check whether the article is talking about a percentage point change or a percentage increase. The distinction matters for understanding whether something has truly grown or just shifted slightly.

Frequently Asked Questions

What if the original value is zero?

You cannot calculate percentage increase when the original value is zero, because you would be dividing by zero. In this case, you can only say the value changed from zero to some number—you cannot express it as a percentage of the original.

Can percentage increase be more than 100%?

Yes. If something doubles, that is a 100% increase. If it triples, that is a 200% increase. If it goes from $10 to $50, the percentage increase is ((50 − 10) ÷ 10) × 100 = 400%.

Is percentage increase the same as percentage change?

Yes. Percentage change is the same calculation and works for both increases and decreases. The term "change" is neutral; the sign of your result (positive or negative) tells you whether it went up or down.

How do I find the new value if I know the original value and the percentage increase?

Rearrange the formula: New Value = Original Value × (1 + (Percentage Increase ÷ 100)). If the original is $100 and the increase is 25%, the new value is $100 × (1 + (25 ÷ 100)) = $100 × 1.25 = $125.