Example
A temperature drops from -20°F to -45°F. What is the percent change?
(-45 - (-20)) / |-20| × 100 = -25 / 20 × 100 = -125
The temperature dropped by 125%.
Example
A bank balance moves from -$500 (overdrawn) to -$200. What is the percentage change?
(-200 - (-500)) / |-500| × 100 = 300 / 500 × 100 = 60
The balance improved by 60%.
Example
A temperature rises from -10°C to 5°C, crossing zero. What is the percentage change?
(5 - (-10)) / |-10| × 100 = 15 / 10 × 100 = 150
The temperature rose by 150%, even though it crossed from below zero to above zero.
When to use this calculator
Use this whenever your starting value is negative — temperatures below zero, debt, or any measurement that can go negative. If both your values are positive, the regular percentage change calculator gives the same result.
Frequently asked questions
Why use the absolute value of the starting value?
Without it, a negative starting value can flip the sign of the result and make an increase look like a decrease, or vice versa.
What if the starting value is exactly zero?
Percentage change is undefined when the starting value is zero, since you'd be dividing by zero.
Does it matter if the ending value is also negative?
No, the formula handles any combination of negative and positive starting and ending values, as long as the starting value isn't zero. Related: percentage change calculator and full formula guide.