Percentage change (increase, decrease, profit, loss)
% change = (new − original) / original × 100. Increase, decrease, profit, loss.
Percentage change is the workhorse of finance and consumer maths. Profit/loss as a percentage uses the cost price as the original.
Worked examples
From £80 to £100: increase of 25%. (100−80)/80 × 100.
From £120 to £90: decrease of 25%. (120−90)/120 × 100.
Cost £40, sold £52: profit of 30%.
Frequently asked questions
Increase by 12%?
Multiply by 1.12. Decrease by 12%: multiply by 0.88. The multiplier method is faster than working out the change separately.
Reverse percentage?
If £120 is 80% of original, original = 120 ÷ 0.80 = 150. See percentagecalculator.co.uk reverse calc.