Percentage Calculator & Percentage Tool

1What is X% of Y?

What is % of = —

2X is what % of Y?

is what % of = —

3Percentage Change (from X to Y)

From to = —

4Increase / Decrease a Number by %

% = —

5Percentage Difference Between Two Numbers

Between and = —

6Find Original (before % increase/decrease)

After result is = —

Quick Reference — Common Percentage Calculations

Question	Formula	Example
What is X% of Y?	(X ÷ 100) × Y	15% of 200 = 30
X is what % of Y?	(X ÷ Y) × 100	30 is 15% of 200
% increase from X to Y	((Y − X) ÷ X) × 100	100→120 = +20%
% decrease from X to Y	((X − Y) ÷ X) × 100	100→80 = −20%
Y increased by X%	Y × (1 + X/100)	200 +15% = 230
Y decreased by X%	Y × (1 − X/100)	200 −15% = 170
Percentage difference	\|X−Y\| ÷ avg(X,Y) × 100	\|100−80\|÷90 = 22.2%
Original before increase	Result ÷ (1 + X/100)	230 after +15% → 200

About the Percentage Calculator

A percentage expresses a number as a fraction of 100. It is one of the most universally used concepts in finance (interest rates, discounts, returns), science, health (body fat %), and everyday life. This calculator bundles six of the most common percentage operations into a single, instant-result tool — no "Calculate" button needed, results update as you type.

Finance Uses

GST / VAT calculations
Discount & sale price
Interest rate comparisons
Investment return (CAGR)
Salary hike calculation

Science & Academic

Concentration in chemistry
Error margin in experiments
Grade percentage / GPA
Survey data analysis
Population change rate

Everyday Life

Restaurant tip calculation
Nutrition labels (% DV)
Body fat & BMI tracking
Battery & storage usage
Price comparison shopping

Key Concepts Explained

Percentage Change Measures relative change from an original value. Positive = increase, negative = decrease. Used for inflation, stock returns, and growth rates.

Percentage Difference Unlike percentage change (which needs a reference direction), percentage difference is symmetric — it measures the gap between two values relative to their average. Used when neither value is the "original."

Reverse Percentage Finding the original value before a percentage was applied. Common use: a product costs ₹230 after 15% GST — the pre-GST price is 230 ÷ 1.15 = ₹200.

What is a Percentage?

A percentage expresses a number as a fraction of 100 — the word comes from Latin per centum ("by the hundred"). Percentages are used everywhere: discounts, interest rates, test scores, tax brackets, and statistics. The key formula is Percentage = (Part / Whole) × 100.

Finance Applications

Discount: 20% off ₹500 = ₹500 × 0.20 = ₹100 saved
GST (18%): Add 18% to base price for total
Interest rate: 8% p.a. on ₹1 lakh = ₹8,000/year
Portfolio gain: Use % change to compare investments

Common Percentage Tricks

X% of Y = Y% of X (e.g., 8% of 25 = 25% of 8 = 2)
To increase by 15%: multiply by 1.15
To decrease by 15%: multiply by 0.85
Back-calculate original: divide by (1 + rate)
Two 10% increases ≠ 20% — it's 21% (compounding)

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