Calculate percentages, percentage increases or decreases, and percentage differences instantly with complete step-by-step formulas.
How to Use This Tool
- Select the calculation mode: Percentage of a number, Percentage Increase/Decrease, or Percentage Difference.
- Enter the primary and secondary values in the numerical inputs.
- View the calculated result and mathematical breakdown instantly.
- Copy the result with a single click.
Formulas & Calculation Methodology
Percentage of a Number: Result = (Percentage / 100) × Base Number
Percentage Increase/Decrease: Change % = ((New Value - Original Value) / |Original Value|) × 100
Percentage Difference: Difference % = (|Value A - Value B| / ((Value A + Value B) / 2)) × 100
Worked Examples
What is 15% of $80?
Scenario: Calculating a 15% tip on an $80 restaurant check.
Step-by-step: (15 / 100) × 80 = 0.15 × 80 = 12
Output: $12.00
Percentage Increase from 50 to 75
Scenario: Measuring web traffic growth from 50k to 75k visitors.
Step-by-step: ((75 – 50) / 50) × 100 = (25 / 50) × 100 = 50%
Output: +50.00% Increase
Supported Formats, Boundaries & Privacy
Inputs & Boundaries: Divisors cannot be zero (division by zero is undefined). Supports positive and negative real numbers.
Local Client-Side Processing: Tool computations and file operations execute 100% locally within your browser sandbox via JavaScript and HTML5 Web APIs. Your input values, uploaded files, and computed results are never transmitted to our web servers. General site access, analytics, and advertising cookies are managed transparently under our Privacy Policy and Cookie Policy.
Frequently Asked Questions
How do I calculate what percentage one number is of another?
Divide the part by the whole and multiply by 100: (Part / Whole) × 100.
What is the formula for percentage increase or decrease?
Percentage change is calculated as: ((New Value – Old Value) / |Old Value|) × 100.
Can this calculator handle negative numbers or decimals?
Yes. It accepts positive numbers, negative values, and arbitrary floating point decimals with full precision.