From one value to another, as a percentage
Work out the percentage change between two numbers, whether prices rose, traffic fell or a salary moved. Shows the direction and the absolute gap.
Percentage change measures movement between a starting figure and a final one. Which number you treat as the start completely changes the answer, and that is where most errors creep in.
Going from 80 to 100 is a 25% rise. Going back from 100 to 80 is a 20% fall. Same two numbers, same gap of 20, different percentages — because the base changed.
What this calculator shows
- The percentage change from your first value to your second
- The raw difference between the two, for a sanity check
- A negative result when the value dropped, so direction is never ambiguous
What to keep in mind
- The change is always measured against the first value as the base.
- If the starting value is zero, percentage change is mathematically undefined — nothing can be a percentage of nothing.
FAQs
Why isn't a 25% rise cancelled by a 25% fall?
Because the fall is calculated on a bigger number. 100 rises to 125, then 25% of 125 is 31.25, leaving you at 93.75 — down almost 6%.
What is the difference between percent change and percentage points?
If a rate moves from 4% to 6%, that is a rise of 2 percentage points but a 50% increase. News reports blur these two constantly.
How do I express a fall as a percentage?
Subtract the new value from the old, divide by the old, then multiply by 100. From 250 to 200 that gives 50 ÷ 250 = 20% down.
Can the change exceed 100%?
Increases can, without limit — doubling is +100%, tripling is +200%. Decreases stop at −100%, which means the value reached zero.
Worked example
A price rise
Input: From 80 to 100
Output: +25%
Note: Reversing it gives −20%. Percentage changes are not symmetrical, which is why 'we lost 50% then gained 50%' leaves you down overall.