Percentage Calculator
Calculate a percentage of any amount, then see the totals after adding or subtracting that percentage.
Loading tool…
How to use Percentage Calculator
Find a share, a rate-based adjustment, or a percentage amount without a spreadsheet. Enter the percentage and the starting amount; the result includes both increase and decrease totals.
- Enter the percentage, such as 20 for 20%.
- Enter the starting amount.
- Calculate the share and the adjusted totals.
Good to know
- Negative amounts and percentages are accepted as signed arithmetic; a negative percentage reverses increase and decrease.
- Numbers use JavaScript floating-point arithmetic. Inputs are limited to 1,000 characters and a magnitude of 1 quadrillion. Results are rounded for display.
Common questions
What formula does the calculator use?
The percentage amount equals the starting amount multiplied by the percentage divided by 100.
Can I use a percentage above 100?
Yes. For example, 150% of 40 is 60. This calculator does not restrict percentages to a whole.
Keep going with related tools
All calculators →Discount Calculator
Find a discounted price, savings, and an optional tax estimate applied after the discount.
CalculatorsProfit Margin Calculator
Calculate gross profit and gross margin from revenue and cost, including loss-making sales.
CalculatorsMarkup Calculator
Turn a cost and a markup rate into a selling price, profit amount, and equivalent gross margin.
MathPercentage Points Calculator
Compare two percentage rates using both percentage-point difference and relative percentage change.
MathPercentage Change Calculator
Measure an increase or decrease relative to an original value, with the signed difference shown.
EducationClass Attendance Policy Roster
Audit weighted attendance across a complete class roster with explicit statuses, cancellations, pending policy and per-session denominator evidence.