Percentage Calculator

The Percentage Calculator is a versatile mathematical tool that helps you solve all types of percentage problems. Whether you need to find what percentage one number is of another, calculate a percentage of a number, or determine percentage increase and decrease, this calculator handles it all instantly.

Percentages are used in virtually every aspect of daily life — from calculating sales tax and tips to understanding interest rates, investment returns, and grade scores. The word 'percent' comes from the Latin 'per centum,' meaning 'by the hundred.'

Understanding percentages is essential for financial literacy. When a store advertises '30% off,' knowing how to quickly calculate the discount can save you money. When your bank offers a 4.5% APY savings account, understanding what that means in dollars helps you make informed decisions.

How the Formula Works

Basic: Percentage = (Part ÷ Whole) × 100. Increase: ((New − Old) ÷ Old) × 100. Decrease: ((Old − New) ÷ Old) × 100.

  • What is X% of Y? → Answer = (X ÷ 100) × Y
  • X is what % of Y? → Answer = (X ÷ Y) × 100
  • Percentage change: ((New Value − Old Value) ÷ Old Value) × 100
  • Finding the whole: Whole = Part ÷ (Percentage ÷ 100)

How to Use This Calculator

  1. Choose the type of percentage calculation you need
  2. Enter the known values in the input fields
  3. Click Calculate to see the result instantly
  4. Use the Clear button to start a new calculation

Tips & Best Practices

  • To find 10% of any number, simply move the decimal point one place to the left
  • To find 1% of any number, move the decimal point two places to the left
  • To calculate tips: 15% = 10% + half of 10%; 20% = 10% × 2
  • A price that goes up 50% and then down 50% does NOT return to the original price — it will be 25% lower

Important Limitations

  • Percentage change is not symmetric — a 50% increase followed by a 50% decrease results in a 25% net decrease
  • Percentages can be misleading with small base numbers (e.g., going from 1 to 2 is a 100% increase)
  • Compound percentage changes cannot be simply added together
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