Calculate percentage difference, percentage increase and decrease between two numbers.
percentage difference
How to use this tool
Type the two numbers you want to compare — prices, scores, measurements or anything else.
This symmetric measure treats neither value as the base, so swapping them gives the same answer.
This directional measure shows increase or decrease from the base you chose in Advanced options.
Use difference when comparing two peers; use change when one value is the “before” and the other is the “after”.
Formula & worked example
50 vs 60: percentage difference = 10 ÷ 55 × 100 = 18.18%. Percentage change from 50 to 60 = +20%, but from 60 back to 50 = −16.67% — change is directional, difference is not.
Limitations — read this before you rely on it
Percentage difference is undefined when both values are zero, and percentage change is undefined when the base value is zero. For very small bases, percentages can look dramatic (1 to 2 is +100%) — always read them alongside the absolute difference.
Frequently asked questions
A symmetric comparison: the absolute difference divided by the average of the two values, times 100. Swapping the values does not change it.
Difference uses the average as the base and is symmetric. Change uses one value as the base and is directional — going up and coming back give different percentages.
(New − old) ÷ old × 100. From 50 to 60: (60 − 50) ÷ 50 × 100 = 20% increase.
Because the base changes: 100 up 50% is 150, but 150 down 50% is 75. To return, you need a 33.33% fall.
Use percentage change for before/after (prices, growth). Use percentage difference when neither value is naturally the base (comparing two products).