how to calculate percentage
Calculating a percentage means applying a base-100 fraction to a value. The formula barely changes with the question, how much is P% of a number, what percent one number is of another, or how much a value changed, but the usual mix-up is not the arithmetic: it is confusing percent change with a percentage point.
The calculator divides 15 by 100, getting 0.15, and multiplies by 200: 0.15 × 200 = 30. It is the same arithmetic used for discounts, simple interest and any P% of V.
The formula (final − initial) ÷ initial × 100 gives (6 − 4) ÷ 4 × 100 = 50%. In percentage points the difference is only 2, showing how the two readings diverge for the same pair of numbers.
120 × 0.80 = 96, four short of the original 100 before the 20% increase. The following discount applies to the already larger base, which is why the value never returns to its starting point.
Multiply the value by the percentage and divide by 100. Example: 20% of 150 = (20 ÷ 100) × 150 = 30. In the "% of a value" mode, just enter 20 and 150.
Because the second percentage is taken from a different base: 100 rises to 120 with the increase, and the following 20% discount is calculated on 120, not on 100, giving 96 instead of the original 100.
A percentage point is the plain subtraction between two percentages, 6% − 4% = 2 points; percent change is that same difference divided by the starting base and multiplied by 100, which gives 50% for a rate rising from 4% to 6%.
Divide the number by the reference and multiply by 100: 30 divided by 150 gives 0.20, which times 100 is 20%. The same formula works to find a test score as a percentage or a budget line's share of the total.
What is P% of a value?
Calculations run in your browser. No data is sent to a server.