Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate the percentage increase or decrease between two values.
+50.00%
Percentage change measures how much a value has grown or shrunk relative to its starting point -- used for everything from price changes to year-over-year growth.
Enter the old value and the new value. The percentage change (positive for an increase, negative for a decrease) appears instantly.
% Change = ((New - Old) / |Old|) × 100
The tool shows a signed percentage, labeled as an increase or a decrease. A positive figure means the new value is higher than the old one, and a negative figure means it is lower. The percentage is always measured against the old value, so the order in which you enter the two numbers matters a great deal. Going from 50 to 75 is a 50 percent increase, but going from 75 to 50 is only a 33.33 percent decrease. The same gap of 25 looks different because the starting point differs.
Imagine a hypothetical monthly subscription that costs 40 and is later discounted to 30. Enter old value 40 and new value 30.
((30 - 40) / 40) × 100 = -25%
The price fell by 25 percent. Now suppose the price later returns from 30 to 40. Enter old value 30 and new value 40: ((40 - 30) / 30) × 100 = +33.33%. This asymmetry is why a 25 percent discount cannot be undone by a 25 percent increase.
Because the formula divides by the absolute value of the old number, the direction is still reported correctly when the starting value is negative. For example, a hypothetical account balance moving from -200 to -100 is an improvement of 100 on a base of 200, which the tool reports as +50 percent. Be careful when presenting such figures to others, though. Percentage change is easiest to interpret when both values are positive, and a change that crosses zero (say from -50 to 50) can produce a number that is technically correct but hard to explain in words. In those cases, quoting the raw difference is often clearer.
Percentage change is undefined when the starting value is zero, because it would require dividing by zero. Growth from nothing to something has no meaningful percentage. If your old value is zero, report the absolute change instead, or choose a different baseline period.
If you know the old value and a percentage change, the new value is old × (1 + change/100). For a 12 percent increase on a hypothetical 250, that is 250 × 1.12 = 280. For a 12 percent decrease, use 250 × 0.88 = 220. You can confirm either result by entering the pair into the calculator and checking that it returns the same percentage.
So the sign of the result always correctly reflects whether the value increased or decreased, even when the old value itself is negative.
No -- percentage change is relative (e.g. 50 to 75 is +50%), while a percentage-point change is the raw difference between two percentages (e.g. 10% to 15% is a 5 percentage-point change but a 50% relative increase).
Because each percentage is measured against a different base. Going from 100 to 150 is +50 percent, but going from 150 back to 100 is a drop of 50 out of 150, which is about 33.33 percent.
Yes, for an increase. If a value more than doubles, the increase exceeds 100 percent. A decrease, however, cannot exceed 100 percent when both values are positive, since the lowest new value would be zero.
Percentage change is undefined because it requires dividing by zero. Report the absolute difference instead, or pick a non-zero baseline period.
Enter the first value as old and the last value as new. Do not add up the individual percentages, because each period compounds on the previous result.
Reference: NIST Weights and Measures