Percentage Change Calculator
Calculate the percentage increase or decrease
Enter the original value
Input the starting or old value — this is your baseline for comparison.
Enter the new value
Input the ending or current value that you want to compare to the original.
Click Calculate
The calculator shows the percentage increase or decrease from the original to the new value.
| Scenario | From | To | Change |
|---|---|---|---|
| Salary raise | $50,000 | $55,000 | +10.00% |
| Sale discount | $80 | $60 | -25.00% |
| Stock price gain | $125 | $150 | +20.00% |
| Population decline | 10,000 | 9,500 | -5.00% |
| Test score improvement | 72 | 85 | +18.06% |
| Weight loss | 180 lbs | 165 lbs | -8.33% |
The Percentage Change Formula
Percentage change measures how much a value has increased or decreased relative to its starting point. The formula is: ((New Value - Original Value) / Original Value) × 100. A positive result means an increase. A negative result means a decrease.
Why Percentage Change Matters
Raw numbers don't tell the whole story. A $10 increase means very different things for a $20 stock versus a $200 stock. Percentage change puts everything on the same scale, making comparisons meaningful across different magnitudes.
Common Uses
People calculate percentage change for price changes, investment returns, salary adjustments, population growth, test score improvements, weight changes, and performance metrics. Any time you need to compare before and after, percentage change gives a clear picture.
Original Value Is the Denominator
Always divide by the original (starting) value, not the new value. This is a common mistake that gives wrong results.
Sign Indicates Direction
Positive means increase, negative means decrease. Some contexts report the absolute value with "increase" or "decrease" specified separately.
Cannot Calculate From Zero
If the original value is zero, percentage change is undefined. You can't divide by zero. Report absolute change instead.
Reversing a Percentage Change
A 50% increase followed by a 50% decrease doesn't return to the original. $100 up 50% is $150. Down 50% from $150 is $75. The base keeps changing.
How do I calculate percentage increase?
Subtract the original from the new value, divide by the original, multiply by 100. Example: from 80 to 100 is (100-80)/80 × 100 = 25% increase.
How do I calculate percentage decrease?
Use the same formula. A decrease gives a negative result. From 100 to 80: (80-100)/100 × 100 = -20%. Report as 20% decrease.
What's the difference between percentage change and percentage points?
Percentage change is relative. Percentage points are absolute differences between percentages. If unemployment goes from 5% to 7%, that's a 2 percentage point increase but a 40% increase ((7-5)/5 × 100).
Can percentage change be more than 100%?
Yes. If something doubles, that's a 100% increase. If it triples, that's a 200% increase. Going from 50 to 200 is a 300% increase.
Why is my percentage change negative?
A negative percentage change means the new value is smaller than the original — it's a decrease. The formula naturally produces negative numbers when new is less than original.
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