How much did it go up or down?
Like rent going from 800 to 920.
Fill in both boxes and we will show how much it changed.
Comparing an old amount with a new one
This works out how much something changed, as a percentage. Rent going from 800 to 920 is a 15% increase; the same numbers the other way round is a 13% decrease.
Put what it was before in the first box and what it is now in the second. We tell you the size of the change and whether it went up or down.
When you would use this
Pay rises, rent increases, bills creeping up, prices changing between visits, or anything you are tracking over time.
It is the opposite of the discount calculator: there you know the percentage and want the new price; here you know both prices and want the percentage.
Common questions
How do I work out a percentage increase?
Put the old amount in the first box and the new one in the second.
By hand: take the old amount away from the new one, divide by the old amount, then multiply by 100.
Why does it need the old amount, not the new one, to divide by?
Because a change is always measured against where you started. Going from 100 to 150 is a 50% rise, but coming back from 150 to 100 is a 33% fall — the same amount of money, a different starting point.
What if the old amount was zero?
Then there is no percentage to give. Any increase from nothing is infinite, so we show no answer rather than a number that would not mean anything.