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How to Calculate Percentage

Percentages are everywhere — in discounts, tax rates, grades, survey results, and financial returns. A percentage simply expresses a number as a fraction of 100. Once you know how to calculate percentage, you can quickly compare values that come in different units or scales. This guide covers the core formula, how to find a given percentage of a number, and how to measure percentage increase or decrease — with examples you will actually use.

The Percentage Formula

The basic percentage formula is:

Percentage = (Part ÷ Whole) × 100

In words: divide the part by the whole, then multiply by 100. This works for any scenario where you have a portion of a total.

For example, if you score 45 out of 60 on a quiz:

Percentage = (45 ÷ 60) × 100 = 0.75 × 100 = 75%

You can also rearrange the formula to find either missing value. If you know the percentage and the whole, you can find the part; if you know the part and the percentage, you can find the whole. That flexibility is what makes percentages so useful.

Here are the three rearranged versions so you can solve for whichever number is missing:

If, say, you know that 30 is 25% of some number, you can find the whole with 30 × 100 ÷ 25 = 120. Knowing all three forms means you never get stuck on a percentage problem.

How to Calculate Percentage Increase and Decrease

To measure how much a value changed, use this variation:

Percentage change = ((New value − Old value) ÷ Old value) × 100

Let's say a product price rises from ₹200 to ₹250.

If the price instead falls from ₹250 to ₹200, the change is −50, so ( −50 ÷ 250 ) × 100 = 20% decrease. Notice that the percentage differs depending on which value is the starting point — a rise from 200 to 250 is 25%, but the same reverse movement is a 20% drop. Always use the original (old) value as the denominator.

Real uses are everywhere: a store offering 30% off, a salary increase of 8%, a sales figure growing 15% year over year, or a test score improving by 10 points. In every case, the same two-value formula gives you the answer.

How to Find What X Percent of Y Is

This is the most common percentage question: given a percentage, what number does it represent? The answer is simple:

Result = (X ÷ 100) × Y

For example, what is 20% of ₹150?

Result = (20 ÷ 100) × 150 = 0.20 × 150 = ₹30

This is exactly what you do mentally when you figure out a tip: 10% of a bill of ₹800 is ₹80, so 5% is ₹40 and 15% is ₹120. Because percentages scale linearly, you can break them into easy chunks — 10%, 5%, 1% — and combine them to solve more complicated cases quickly. Calculate a discount the same way: if a ₹1,200 jacket is 25% off, the saving is 1,200 × 0.25 = ₹300, leaving ₹900 to pay.

Calculating percentages repeatedly, especially with sales tax, discounts, or multi-step statistics, is faster and more accurate with a dedicated tool. Our percentage calculator handles the math instantly so you can focus on the decision, not the arithmetic.

A useful shortcut for mental math is to remember that "per cent" literally means "per hundred." So a percentage is just a ratio scaled to a hundred. That is why 25% equals one quarter, 50% equals one half, and 75% equals three quarters — you can often convert a percentage into a simple fraction and skip the arithmetic entirely. Ten percent is simply moving the decimal point one place left, which makes it the easiest percentage to compute on the fly.

One final distinction worth knowing is the difference between a percentage and a percentage point. If a bank raises its interest rate from 5% to 7%, that is a 2 percentage point increase, even though it is a 40% relative rise. Confusing the two is a common mistake in finance and in news reporting — so when someone quotes a percentage change, check whether they mean the absolute change or the relative change.

Mastering how to calculate percentage gives you an edge in everyday budgeting, shopping, and reading the news. With just the three simple forms above — the base formula, percentage change, and finding a percentage of a number — you can handle almost any percentage problem that comes your way.