Percentage of a value
Use this when you want to find a percentage of a known value.
(percentage / 100) × value Example: 15% of 240 is 36.
Math · Runs in your browser
Local processing Percentage Calculator
Calculate percentages, ratios, and percentage change privately in your browser.
Browser calculator
Calculates on this device Find your answer
Your result
Calculated locally
Your answer will appear here.
Formula: choose a calculation to see its method.
The short version
Calculate a percentage in seconds.
Choose the kind of percentage you need, enter finite numbers, and the answer appears locally in your browser. Negative values are supported when they make mathematical sense.
Percent ratio
Use this to express one number as a percentage of another.
(part / whole) × 100 Example: 18 is 25% of 72.
Percentage change
Use this to compare a starting value with a new value.
((new - original) / original) × 100 Example: moving from 80 to 92 is a 15% increase.
Helpful questions
Percentage calculator FAQs
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 18 ÷ 72 × 100 = 25%.
Can I use negative numbers?
Yes. The calculator accepts finite negative decimals. The sign of the result follows the selected formula and inputs.
Why does the displayed answer have limited decimals?
JavaScript uses binary floating-point numbers, so some decimal fractions cannot be represented exactly. The display rounds to 10 decimal places to keep answers readable.
Does this calculator store or send my numbers?
No. Calculation runs in your browser, and the tool has no account, persistence, server calculation, or input/output transmission.
Know before you use
Clear, simple boundaries
What it does
A formatted percentage or calculated value with its formula context.
What it needs
Percentage: The percentage to apply to a value. Value: The number to calculate a percentage of. Part: The part of the whole you want to express as a percentage. Whole: The complete amount used as the ratio denominator. Original value: The starting value for a percentage change. New value: The ending value for a percentage change.
Privacy
Processing happens locally in your browser. No text or files are transmitted.
Storage
This tool does not persist your work.