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MonoCalc

Percentage Calculator

Percentage (%)
Number

Result

Formula:

25% of 80 = 0.25 × 80 = 20

Answer:

Result
20

About the tool

🧮 Percentage Calculator – Solve Common Percentage Problems

Need to solve percentage problems? The Percentage Calculator helps you quickly solve the three most common percentage calculations with step-by-step explanations.

This guide explains what percentages are, how they're calculated, and walks you through using our free online percentage calculator to solve percentage problems.

📘 What Are Percentages?

A percentage is a number expressed as a fraction of 100. The symbol "%" represents percentage. For example, 50% means 50 out of 100, or half of the total.

Percentages are used to express proportions, ratios, and changes in values in a standardized way.

⚙️ How the Percentage Calculator Works

Our percentage calculator offers three calculation modes:

  1. % of - Calculate what is X% of Y
  2. % of total - Calculate X is what percent of Y
  3. % change - Calculate the percentage increase or decrease between two values

🧩 Key Features

  • ⚡ Instant calculations for all common percentage problems
  • 📊 Step-by-step formulas with substituted values
  • 🔄 Three calculation modes in one tool
  • 📱 Mobile and desktop-friendly interface
  • 🔐 Client-side only — no data is ever uploaded

💡 Common Percentage Formulas

1. Finding a percentage of a number

To find X% of Y:

Result = (X / 100) × Y

Example: 25% of 80 = (25 / 100) × 80 = 0.25 × 80 = 20

2. Finding what percent one number is of another

To find what percent X is of Y:

Result = (X / Y) × 100%

Example: 45 is what percent of 120? (45 / 120) × 100% = 0.375 × 100% = 37.5%

3. Finding percentage change

To find the percentage change from original value (O) to new value (N):

Result = ((N - O) / O) × 100%

Example: Original value: 80, New value: 96
((96 - 80) / 80) × 100% = (16 / 80) × 100% = 0.2 × 100% = 20% increase

🌟 Practical Applications of Percentages

  • 💰 Finance: Calculating discounts, taxes, interest rates, and investment returns
  • 📊 Statistics: Expressing proportions of data in a standardized way
  • 🏪 Business: Profit margins, growth rates, market share
  • 🏫 Education: Test scores, grade distributions
  • 🏥 Health: Body fat percentage, medication dosages

🔄 How to Use the Percentage Calculator

  1. Select the calculation mode that matches your problem
  2. Enter the required values in the input fields
  3. The calculator will instantly compute the result
  4. View the step-by-step calculation with the formula
  5. Use the copy button to save your result

✅ Tips for Working with Percentages

  • Remember that percentages are always relative to some whole (100%)
  • When calculating percentage change, the original value is always the reference point
  • A negative percentage change indicates a decrease
  • To convert a decimal to a percentage, multiply by 100
  • To convert a percentage to a decimal, divide by 100

Frequently Asked Questions

  • Is the Percentage Calculator free ?

    Yes, Percentage Calculator is totally free :)

  • Can i use the Percentage Calculator offline ?

    Yes, you can install the webapp as PWA.

  • Is it safe to use Percentage Calculator ?

    Yes, any data related to Percentage Calculator only stored in your browser(if storage required). You can simply clear browser cache to clear all the stored data. We do not store any data on server.

  • What is a percentage?

    A percentage is a number or ratio expressed as a fraction of 100. It is denoted using the percent sign (%). For example, 50% means 50 out of 100, or half of the total.

  • How do I calculate what is X% of Y?

    To calculate X% of Y, multiply Y by X/100. For example, to find 25% of 80: 25/100 × 80 = 0.25 × 80 = 20.

  • How do I calculate X is what percent of Y?

    To calculate what percent X is of Y, divide X by Y and multiply by 100. For example, to find what percent 45 is of 120: (45 ÷ 120) × 100 = 0.375 × 100 = 37.5%.

  • How do I calculate percentage change?

    To calculate percentage change (increase or decrease), subtract the original value from the new value, divide by the original value, and multiply by 100. For example, if a value changes from 80 to 96: ((96 - 80) ÷ 80) × 100 = (16 ÷ 80) × 100 = 0.2 × 100 = 20% increase.

  • Why is my percentage change negative?

    A negative percentage change indicates a decrease from the original value to the new value. For example, if a value changes from 100 to 75, the percentage change is ((75 - 100) ÷ 100) × 100 = -25%, indicating a 25% decrease.