๐ Percentage Increase Calculator
By ToolNimba Editorial Team ยท Updated 2026-06-21
Percentage increase = (new - old) / |old| x 100.
A percentage increase tells you how much a value has grown relative to where it started, expressed as a percent of the original amount. This calculator works two ways: paste an original value and a new value to find the exact percentage change, or enter a starting number and a percent to see the increased total. It handles negatives and a zero starting value safely, so you always get a sensible answer.
What is the Percentage Increase Calculator?
Percentage increase compares the size of a change to the size of the thing that changed. The formula is straightforward: subtract the original value from the new value to get the raw difference, divide that difference by the absolute value of the original, then multiply by 100 to turn the ratio into a percent. Going from 50 to 75 is a difference of 25, and 25 divided by 50 is 0.5, which is a 50 percent increase. If the result comes out negative, the value actually fell, so it is a percentage decrease rather than an increase.
The word original carries a lot of weight here. Percentage increase is always measured against the starting point, never the ending point, and that is the single most common source of mistakes. A jump from 50 to 75 is a 50 percent increase (25 out of 50), but the reverse move from 75 back to 50 is only a 33.3 percent decrease (25 out of 75), because the base is now larger. The same absolute change produces different percentages depending on which number you divide by, which is exactly why a stock that drops 50 percent has to rise 100 percent to recover.
There are two distinct questions people bring to a tool like this, and the calculator handles both. The first is find the change: you already know the before and after numbers and want the percent that connects them. The second is apply a percent: you know a starting value and a growth rate and want the final figure, such as adding a 15 percent tip, a 20 percent markup, or an 8 percent raise. Applying a p percent increase means multiplying by (1 + p / 100), so a 200 value increased by 15 percent becomes 200 x 1.15 = 230.
Edge cases matter for getting trustworthy results. When the original value is zero, percentage increase is mathematically undefined because you would be dividing by zero, so the tool flags this rather than printing a misleading number. When the original is negative, the calculator divides by its absolute value so the sign of the answer still reflects the real direction of the change. These guards mean you can drop in real-world data, sign and all, without the result quietly breaking.
When to use it
- Working out a salary raise or price rise as a percent, for example finding that a move from 50,000 to 56,000 is a 12 percent increase.
- Applying a markup, tip, or tax rate to a base figure to get the final total without doing the multiplication by hand.
- Comparing month-over-month or year-over-year growth in sales, traffic, followers, or any metric.
- Checking homework or finance figures where you need both the exact difference and the percent it represents.
How to use the Percentage Increase Calculator
- Choose a mode: "Find the change" if you have two values, or "Apply a percent" if you have a starting value and a rate.
- In Find the change, type the original value and the new value; the tool shows the percent change, the direction, and the difference.
- In Apply a percent, type the starting value and the percent to increase by; the tool shows the new total and the increase amount.
- Read the result panel, then use Copy result to put the numbers on your clipboard, or Swap to reverse the two values.
Formula & method
Worked examples
A product price rises from 80 dollars to 100 dollars. What is the percentage increase?
- Find the difference: 100 - 80 = 20.
- Divide by the original value: 20 / 80 = 0.25.
- Multiply by 100: 0.25 x 100 = 25.
- The difference is positive, so this is an increase.
Result: 25 percent increase (the price went up by 20 dollars).
You earn 200 dollars and want to add a 15 percent increase. What is the new amount?
- Convert the percent to a multiplier: 1 + 15 / 100 = 1.15.
- Multiply the starting value: 200 x 1.15 = 230.
- The increase amount alone is 200 x 0.15 = 30.
Result: New amount is 230 dollars, an increase of 30 dollars.
Common before and after values and their percentage increase
| Original | New | Difference | Percentage increase |
|---|---|---|---|
| 50 | 75 | +25 | +50% |
| 80 | 100 | +20 | +25% |
| 100 | 150 | +50 | +50% |
| 200 | 230 | +30 | +15% |
| 1000 | 1100 | +100 | +10% |
| 40 | 30 | -10 | -25% (a decrease) |
A starting value of 100 increased by a percent
| Percent increase | Multiplier | Increase amount | New value |
|---|---|---|---|
| 5% | 1.05 | +5 | 105 |
| 10% | 1.10 | +10 | 110 |
| 15% | 1.15 | +15 | 115 |
| 25% | 1.25 | +25 | 125 |
| 50% | 1.50 | +50 | 150 |
| 100% | 2.00 | +100 | 200 |
Common mistakes to avoid
- Dividing by the new value instead of the original. Percentage increase is always measured against the starting amount. For a move from 50 to 75 you divide 25 by 50, not by 75. Dividing by the new value gives 33.3 percent, which answers a different question entirely.
- Assuming an increase and a decrease of the same percent cancel out. Increasing 100 by 20 percent gives 120, but decreasing 120 by 20 percent gives 96, not 100. The percentages apply to different bases, so they do not undo each other.
- Forgetting to add the original back when applying a percent. A 15 percent increase on 200 is not 30. The 30 is just the increase amount. The new total is 200 + 30 = 230, which is 200 x 1.15. Multiply by (1 + percent / 100), not by percent / 100 alone.
- Treating a drop as an increase. If the new value is smaller than the original, the formula returns a negative number. That is a percentage decrease, not an increase. Always check the sign and the direction label before reporting the figure.
Glossary
- Percentage increase
- How much a value has grown compared with its original size, expressed as a percent of that original value.
- Original value
- The starting or before number that the change is measured against. It is the denominator in the percentage increase formula.
- New value
- The ending or after number. The difference between it and the original drives the percentage.
- Difference
- The raw change, found by subtracting the original value from the new value. A positive difference is an increase.
- Multiplier
- The factor (1 + percent / 100) you multiply by to apply a percent increase, for example 1.15 for a 15 percent rise.
- Percentage decrease
- The result when the new value is smaller than the original, producing a negative percentage change.
Frequently asked questions
How do I calculate percentage increase?
Subtract the original value from the new value, divide that difference by the original value, then multiply by 100. For example, from 50 to 75 the difference is 25, and 25 / 50 x 100 = 50, so it is a 50 percent increase.
What is the formula for percentage increase?
Percentage increase = (new value - original value) / original value x 100. If the answer is positive it is an increase; if it is negative the value actually decreased.
How do I increase a number by a percent?
Multiply the number by (1 + percent / 100). To increase 200 by 15 percent, compute 200 x 1.15 = 230. The increase amount on its own is 200 x 0.15 = 30.
Why is the percentage increase different when I reverse the two numbers?
Because the percentage is always divided by the original value, and reversing the numbers changes which one is the base. Going 50 to 75 is a 50 percent increase, but 75 to 50 is only a 33.3 percent decrease, since 25 is now compared with the larger base of 75.
What happens if the original value is zero?
Percentage increase is undefined when the original value is zero, because you would be dividing by zero. Any growth from zero is effectively an infinite percentage, so the calculator flags this case instead of showing a misleading number.
Can this calculator handle negative numbers?
Yes. It divides by the absolute value of the original so the sign of the result still shows the true direction of the change, and in apply mode a negative percent simply reduces the starting value.