💯 Percent Tool

Percentage Calculator

Find % of a number, calculate change & increase/decrease, or convert any ratio to percent — instantly.

Find X% of Y → e.g. "What is 20% of 150?"

Percentage (X)

Number (Y)

💯 Result

-- Answer

--Value A

--Value B

--Result

💡

Context

History

No calculations yet.

All calculations use standard floating-point arithmetic. Results are rounded to 6 decimal places for display.

How does this percentage calculator work?

This tool covers the four most common percentage problems. Each formula is applied with full floating-point precision, and results are rounded to 6 decimal places for display.

X% of Y = (X ÷ 100) × Y
X is what % of Y = (X ÷ Y) × 100
% Change = ((New − Old) ÷ |Old|) × 100
Reverse % = Value ÷ (Percent ÷ 100)

💰 Discounts & Offers

Find the sale price after a 20% discount or calculate how much you save. Use "X% of Y" mode.

📊 Data & Statistics

Turn raw counts into percentages — exam scores, survey responses, market share — using "X is what % of Y".

📈 Growth & Decline

Measure revenue growth, follower increase, or stock movement with the % Change calculator.

🔁 Reverse Calculations

Know the part and the percentage? Find the original total using the Reverse % mode instantly.

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 = (150 × 20) ÷ 100 = 30. Use the "X% of Y" tab for instant results.

How do I calculate percentage change?

Percentage change = ((New Value − Old Value) ÷ Old Value) × 100. A positive result means an increase; negative means a decrease. The % Change tab handles both automatically.

What is percentage increase?

Percentage increase = ((New − Old) ÷ Old) × 100. For example, a price going from 80 to 100 is a 25% increase. The % Change tab shows whether the result is an increase or decrease.

How do I find what percentage one number is of another?

Divide the part by the whole and multiply by 100. For example, 30 out of 150 = (30 ÷ 150) × 100 = 20%. Use the "X is what % of Y" tab.

How do I calculate the original number from a percentage?

Divide the known value by the percentage and multiply by 100. If 30 is 20% of X, then X = (30 ÷ 20) × 100 = 150. Use the Reverse % tab for this.