Percentage Change Calculator
Use this tool to calculate percentage increase or percentage decrease between two values.
Formula used: ((new - old) / old) × 100
If you need to quickly calculate percentage change, this calculator gives you the answer instantly and explains whether your value went up, went down, or stayed the same. It works well for prices, revenue, test scores, traffic, weight, and many other day-to-day comparisons.
What is percentage change?
Percentage change tells you how much a value has changed relative to where it started. Instead of looking only at the raw difference, percentage change puts that difference into context. A change of 10 can be huge if you started at 20, but small if you started at 1,000.
- Positive result = percentage increase
- Negative result = percentage decrease
- Zero = no change
Percentage change formula
The standard formula is:
Percentage Change = ((New Value - Old Value) / Old Value) × 100
You can compute it in three simple steps:
- Find the absolute change: new - old
- Divide by the old value
- Multiply by 100 to convert to percent
How to use this calculator
Step-by-step
- Enter your starting number in Starting Value.
- Enter your ending number in Ending Value.
- Choose how many decimal places you want.
- Click Calculate to view results.
The output includes:
- Absolute change (the raw numeric difference)
- Percentage change
- Direction (increase, decrease, or no change)
Worked examples
Example 1: Price increase
A product rises from $80 to $100.
- Absolute change = 100 - 80 = 20
- Percentage change = (20 / 80) × 100 = 25%
This is a 25% increase.
Example 2: Traffic decrease
A website drops from 50,000 monthly visits to 42,500.
- Absolute change = 42,500 - 50,000 = -7,500
- Percentage change = (-7,500 / 50,000) × 100 = -15%
This is a 15% decrease.
Example 3: No change
If a value remains at 300 and ends at 300, the absolute change is 0 and the percentage change is 0%.
Percentage change vs percentage points
These two are often confused:
- Percentage points are direct differences between percentages (for example, from 40% to 45% is +5 percentage points).
- Percentage change compares relative growth (from 40% to 45% is a 12.5% increase because 5/40 = 0.125).
Use percentage points for comparing rates themselves, and percentage change for relative movement.
Common mistakes to avoid
- Using the new value as the denominator instead of the old value.
- Mixing up increase and decrease signs.
- Forgetting to multiply by 100.
- Trying to compute standard percentage change when the starting value is zero.
Special case: when starting value is zero
If your old value is 0 and your new value is not 0, the standard percentage change formula is undefined because dividing by zero is not valid. In those situations, report the absolute change instead, or use an alternative metric depending on your field.
FAQ
Can this calculator handle negative numbers?
Yes. The calculator computes mathematically correct results with negative values. Just interpret outcomes carefully, because “increase/decrease” can be less intuitive when the baseline is negative.
What if I need percentage increase only?
You can still use this tool. If the result is negative, then the value did not increase; it decreased.
Is absolute change included?
Yes. You get both the absolute change and the percentage change so you can understand both magnitude and relative movement.
Final thoughts
A reliable calculate percentage change calculator saves time and reduces formula mistakes. Whether you are tracking expenses, sales, grades, performance, or personal goals, percentage change is one of the most useful quick metrics you can use.