StraightToolsPercentage Calculator
Find a percentage of a number and see percentage change.
Percentage formula
To find x% of y, multiply y by x ÷ 100.
When to use this tool
Use the percentage calculator for everyday questions such as finding 20% of a number or understanding how much one value changed relative to another.
How the result is calculated
To find x percent of y, multiply y by x/100. Percentage change is the difference between the new and original values divided by the original value, then multiplied by 100.
Worked example
Twenty percent of 250 is 50 because 250 × 0.20 = 50. If a price rises from $200 to $250, the increase is 25%, not 20%, because the $50 change is measured against the original $200.
What to keep in mind
Be careful about the base value. Percentage increase, percentage points, and “percent of total” answer different questions and are not interchangeable.
About our calculations
StraightTools is designed to show the method behind the answer, not just the result. Inputs are handled in your browser for this tool. For important financial, legal, medical, tax, safety, or contractual decisions, verify the result with an appropriate authoritative source or qualified professional.