Percentage Calculator

Calculate percentages in 4 different ways

About the Percentage Calculator

A percentage calculator is one of the most versatile math tools for everyday use. Whether you're working out a restaurant tip, calculating a tax amount, tracking investment growth, or analyzing business data, percentages appear everywhere.

This free online percentage calculator covers four distinct calculation types in a single interface. Each mode handles a different real-world question — select the one that matches your situation, enter two numbers, and get an instant result with the formula displayed.

All calculations happen instantly in your browser with no data sent to any server, making it fast, private, and available offline.

How to Use the Percentage Calculator

  1. Choose a calculation mode — pick from the four buttons at the top: "What is X% of Y?", "X is what % of Y?", "% change from X to Y", or "Increase/decrease X by Y%".
  2. Enter your two values — type numbers into the two input fields. Labels update automatically to tell you which value goes where.
  3. Read the result instantly — the answer appears in the blue result panel as you type, along with the full formula so you can verify the math.
  4. Copy the result — click the Copy button in the result panel to copy the number to your clipboard.
  5. Try quick examples — click any of the preset example buttons to load a worked calculation and see how each mode works.

Common Use Cases

Shopping & Discounts

Calculate how much you save with a 20% off sale. Use "What is X% of Y?" to find the discount amount, then subtract from the original price.

Tax & Tips

Find 8.5% sales tax on a $49 item, or calculate a 18% restaurant tip. "Increase X by Y%" gives you the new total with tax or tip included.

Business & Finance

Track revenue growth from last quarter to this quarter with "% change from X to Y". Negative results indicate a decline; positive results show growth.

Grades & Test Scores

Got 43 out of 55 on an exam? Use "X is what % of Y?" to instantly find your score percentage without doing long division by hand.

Weight & Health Goals

Calculate percentage of body weight lost or gained, or find what percentage of your daily calorie goal a meal represents.

Investment Returns

Calculate the percentage return on an investment by comparing the starting value to the current value using the % change mode.

Frequently Asked Questions

How do I calculate what percent one number is of another?

Select "X is what % of Y?", enter the part as X and the whole as Y. For example, to find what percent 25 is of 200: enter 25 in X and 200 in Y. The formula is (X ÷ Y) × 100, giving 12.5%.

How do I calculate percentage increase or decrease?

Use the "% change from X to Y" mode. Enter the original value as X and the new value as Y. A positive result means an increase; a negative result means a decrease. The formula is ((Y − X) ÷ |X|) × 100.

How do I add a percentage to a number (e.g., add VAT)?

Use "Increase/decrease X by Y%". Enter the base amount as X and the percentage as Y. For a £120 item with 20% VAT: X = 120, Y = 20. The result is the total including VAT (£144).

Can I calculate a percentage decrease using this tool?

Yes. In "Increase/decrease X by Y%" mode, enter a negative value for Y. For example, to decrease 500 by 30%, set X = 500 and Y = −30. The result is 350.

What is the formula for calculating a percentage of a number?

The formula is: Result = (Percentage ÷ 100) × Number. For example, 15% of 80 = (15 ÷ 100) × 80 = 12. This calculator shows the full formula beneath every result.

Why does the % change mode show a red result?

The result turns red when the percentage change is negative (a decrease). This visual indicator makes it easier to spot at a glance whether a value went up or down.

How many decimal places does this calculator show?

Results are shown with up to 6 decimal places when needed. Whole-number results display without decimals, keeping the output clean and easy to read.

Mode

Quick Examples

Tips

• Use negative % to decrease a value

• Results update as you type

• Click any example to load it