The basic percentage formula
To find a percentage of a number, convert the percentage to a decimal by dividing by 100, then multiply by the base number. For example, 18% becomes 0.18.
Worked example
To find 18% of 450, calculate 450 × 0.18. The result is 81. This same method works for prices, marks, survey results, commissions, and many other everyday calculations.
Percentage increase
First find the increase as a percentage of the original value. The percentage change formula is (new value − original value) ÷ original value × 100.
Percentage decrease
For a decrease, subtract the new value from the original value, divide by the original value, and multiply by 100. Keep the original value as the denominator.
Try the calculator
Use the calculator below when you want to apply the formula to your own numbers.
Open Percentage Calculator →Methodology: QuickSolve guides explain common mathematical formulas in plain language. Where institutions, lenders, employers or accounting systems use their own rules, those official rules take priority.