Percentage Calculator
Calculate percentages, determine what percentage one number is of another, or find the percentage change between two values.
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This online percentage calculator helps you solve three common everyday math problems quickly and accurately. You can calculate a percentage of any number, find what percentage one value represents out of a total, or measure the percentage change between an original value and a new amount.
Enter finite decimal values into the input fields and select the calculation type that fits your task. When finding a percentage of a total, the calculator applies the specified percentage to your total number. When determining a percentage ratio, it divides your value by the total to show the corresponding percentage share. When calculating percentage change, it treats the total field as the starting baseline to evaluate the increase or decrease.
Results round to ten decimal places using half-up rounding, giving you clean figures for discounts, taxes, tips, test scores, and growth metrics. Non-finite values and zero divisors produce clear validation notices.
Instructions
- Enter your primary numeric amount into the Value field.
- Enter the comparison base or starting number into the Total or original value field.
- Choose your desired operation from the Calculation menu: Percent Of, Is What Percent, or Percent Change.
- View the calculated percentage or numeric output displayed in the result area.
Examples
- Calculate a 15% tip on an $80 restaurant bill by entering 15 as Value, 80 as Total, and selecting Percent Of to get 12.
- Find your test grade percentage after scoring 42 out of 50 by entering 42 as Value, 50 as Total, and selecting Is What Percent to get 84%.
- Measure price increase from $50 to $65 by entering 65 as Value, 50 as Total or original value, and selecting Percent Change to get a 30% increase.
FAQ
How do I calculate what percentage a number is of a total?
Enter the part in the Value field, enter the whole amount in the Total or original value field, and select Is What Percent from the Calculation menu.
Can I use negative numbers or decimals?
Yes, finite decimal values and negative numbers are accepted across all input fields.
Why does a calculation show an error when total is zero?
Finding a percentage ratio or percentage change requires dividing by the base amount. Division by zero is mathematically undefined, so entering zero in the total field produces a validation notice.
How are output values rounded?
Calculated results are rounded to ten decimal places using standard half-up rounding.