semkuPercentage calculator
Choose the calculation you need. Each result shows the numbers used, the base and the formula.
Calculation rules and supported formats
To find X% of Y, calculate X ÷ 100 × Y. The result is an amount, not another percentage. For example, 20 ÷ 100 × 200 = 40.
To find what percentage a part is of a whole, calculate part ÷ whole × 100. For example, 18 ÷ 24 × 100 = 75%. The whole cannot be zero. If the whole is negative, its sign stays in the denominator.
For percentage change, calculate (new value − starting value) ÷ abs(starting value) × 100. Here, abs means absolute value: abs(−80) is 80. A change from 80 to 100 is +25%; a change from 100 to 80 is −20%. The starting value cannot be zero. For a negative starting value, this calculator uses its absolute value as the base. This convention is stated with the result.
To compare two percentages, subtract the starting percentage from the new percentage. The difference is measured in percentage points. Relative percentage change is (new percentage − starting percentage) ÷ abs(starting percentage) × 100, using the numbers as entered: use 20 for 20%. From 20% to 25%, the difference is 5 percentage points and the relative change is +25%. If the starting percentage is zero, only the percentage-point change is defined.
For percentage difference, calculate abs(A − B) ÷ ((A + B) ÷ 2) × 100. The order of the two values does not matter. For example, 50 and 70 differ by 20 ÷ 60 × 100 ≈ 33.33%. If A + B is zero, the percentage difference is not defined. If the average is negative, the result is negative.
The percentage table shows 1%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 90% and 100% of the base value. Each row is percentage ÷ 100 × base value. For example, 25% of 250 is 62.5.
Increase, decrease and no change describe the exact numerical comparison before rounding. They do not say whether a change is favourable. A small increase may be displayed as 0% after rounding and still be labelled Increase.
Calculations use the full input values without intermediate rounding. Each displayed result is rounded separately to the selected decimal places. Ties are rounded away from zero: 0.005 becomes 0.01 and −0.005 becomes −0.01 to two decimal places. Trailing zeros are kept. No rounding needed describes the displayed number only. The ≈ symbol marks an approximate result.
Enter whole numbers or decimals, with an optional sign. Use a full stop as the decimal separator. Commas can separate thousands in the whole-number part: use one to three digits with no leading zero in the first group, then exactly three digits in each following group. For example, enter 1,234.5. Fractions and scientific notation are not supported as inputs. A single final % sign is ignored without changing the value of the number. The whole-number part can contain up to 15 digits. Results use a decimal point and commas as thousands separators.
Calculation rules v1
Frequently asked questions
- What is the formula for a percentage?
- To express a part as a percentage of a whole, divide the part by the whole and multiply by 100. For example, 18 out of 24 is 18 ÷ 24 × 100 = 75%. The whole cannot be zero.
- How do I calculate a percentage of a number?
- Divide the percentage by 100, then multiply by the number. For example, 20% of 200 is 20 ÷ 100 × 200 = 40. Choose X% of Y and enter 20 and 200.
- How do I calculate a percentage increase or decrease?
- Choose Percentage change from A to B. With a positive starting value, subtract it from the new value, divide by the starting value and multiply by 100. From 80 to 100, the increase is 25%. From 100 to 80, the decrease is 20%. For a negative starting value, this calculator uses its absolute value as the denominator and shows a note.
- How do I calculate a percentage from marks?
- Choose X is what % of Y. Enter the marks earned as the part and the total possible marks as the whole. For example, 18 out of 24 is 75%. This calculates the percentage only; it does not apply grade boundaries or weighting.
- Is percentage difference the same as percentage change?
- Percentage difference often uses the average of two positive values as its base. Percentage change uses a starting value. This calculator uses a starting value for change and shows percentage points separately when comparing two rates. A move from 20% to 25% is 5 percentage points and a 25% relative increase. To use the average of two values as the base, choose Percentage difference.
- How do I calculate a discount?
- Use the Percent off calculator to find the sale price and savings, recover an original price, or calculate the discount percentage from two prices.
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For details, see the privacy policy.
Calculations run in your browser without sending your calculation inputs or results to the server. The base and formula appear with the result. See “Privacy on this page” for information about access data.