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HomemathPercentage Calculator

Percentage Calculator

Find percentage of a number, percentage change, reverse percentages, and what percent one value is of another — all in one tool.

One tool for every percentage problem: find X% of a number, calculate percentage increase or decrease, reverse percentages, and determine what percent one value is of another. No more memorizing three different formulas.

Percentage math appears everywhere — sales discounts, tax rates, grade curves, tip calculations, and business markup. Students and professionals use this daily during shopping, reporting, and exam prep.

Example workflows: a 30% off $89 jacket costs $62.30; a price rising from $50 to $65 is a 30% increase; if 24 is 60% of a number, the original is 40.

Results update as you type. Free, browser-based, no account — bookmark for quick access during homework or Black Friday shopping.

What is X% of Y?

Formula

% of N = (P ÷ 100) × N · % change = ((new − old) ÷ old) × 100 · Reverse: original = part ÷ (P ÷ 100)

Common Uses

  • ✓Calculate sale discounts and final prices
  • ✓Find percentage increase or decrease
  • ✓Reverse percentage (find original before tax or markup)
  • ✓Grade and test score percentages
  • ✓Business markup and margin checks

How to Use the Percentage Calculator

  1. 1

    Choose calculation type

    Select whether you want % of a number, % change, or reverse %.

  2. 2

    Enter your values

    Input the numbers relevant to your calculation.

  3. 3

    Get instant result

    The percentage result is calculated and displayed immediately.

💡 Tips & Tricks

  • •Use percentage change to track price increases, discounts, or growth rates.
  • •For discounts: subtract the discount % from 100%, then multiply by the original price.
  • •Percentage calculators are essential for tax, tip, and commission calculations.

Frequently Asked Questions

How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 20% of 150 = (20 × 150) / 100 = 30.
How do I calculate percentage change?
Percentage change = ((New Value – Old Value) / Old Value) × 100. A positive result is an increase; negative is a decrease.
What is a reverse percentage calculation?
A reverse percentage finds the original value before a percentage was applied. For example, if 80 is 40% of a number, the original = 80 / 0.40 = 200.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 is what % of 150? = (30/150) × 100 = 20%.

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