Percent Change Calculator (Percentage Increase & Decrease)
Updated · Free · No sign-up · Runs in your browser
Find the percentage increase or decrease between two values: prices, salaries, test scores, traffic or sales. Negative starting values are handled correctly.
Two more modes: percent difference between two values (no "old" or "new"), and increasing or decreasing a number by a percentage.
+30%
Increase of 15 (from 50 to 65)
Negative starting values are divided by their absolute value, so −50 → −25 shows +50% (an improvement).
Worked examples
Price goes from $50 to $65
- (65 − 50) ÷ 50 × 100
→ +30%
Salary drops from 80,000 to 60,000
- (60,000 − 80,000) ÷ 80,000 × 100
→ -25%
Loss shrinks from −50 to −25
- (−25 − (−50)) ÷ |−50| × 100
→ +50%
Increase 200 by 15%
- 200 × 1.15
→ 230
Percentage increase formula
Percent change = (new − old) ÷ |old| × 100. A positive result is an increase, a negative result a decrease. A change from 0 has no percentage.
Percentage change with negative numbers
Dividing by the absolute value of the old number keeps the sign meaningful: going from −50 to −25 is a +50% change (it went up). Some textbooks divide by the raw old value instead, which flips the sign.
Percent change vs. percent difference vs. percentage points
- Percent change compares a new value to an old one.
- Percent difference compares two values with no direction: |a − b| ÷ average × 100.
- If both values are already percentages (5% → 7%), the change is 2 percentage points but a 40% increase.
Frequently asked questions
How do I calculate percentage increase?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 50 to 65: 15 ÷ 50 × 100 = 30%.
How do I calculate percentage decrease?
Use the same formula; the result is negative. From 80 to 60: −20 ÷ 80 × 100 = −25%, a 25% decrease.
Why is 50% up then 50% down not back to the start?
Each percentage applies to a different base. 100 + 50% = 150, then 150 − 50% = 75.
What is percent difference?
The gap between two values relative to their average, used when neither value is the "original". 40 and 60 differ by 20 ÷ 50 = 40%.
Can the starting value be negative?
Yes. This calculator divides by the absolute value of the starting number, so an improvement from −50 to −25 shows as +50%.
Is my data stored?
No. Calculations run in your browser only.