Compare an original and new value to find the percentage increase or decrease instantly.
Percentage change = (new − old) ÷ |old| × 100.
Subtract the original value from the new value, divide that change by the absolute original value, then multiply by 100. A positive result is a percentage increase; a negative result is a percentage decrease.
Percentage change is always measured against the starting value. Going from 100 to 125 is a 25% increase, but going from 125 back to 100 is a 20% decrease because the denominator is different.
If the original value is zero, percentage increase or decrease is mathematically undefined because the formula would require division by zero. The calculator reports that case explicitly.
Subtract the original value from the new value, divide by the absolute original value, then multiply by 100.
Yes. When the new value is lower than the original value, the result is shown as a percentage decrease.
Percentage change from zero is undefined because the standard formula requires division by the original value.