Percentage Calculator

Q: What is 15% of 200?

30. Multiply 200 by 0.15 — it's the calculation this page opens with.

Q: What is 20% of 50?

10. It's the same pattern people use for tips: 20% of a $50 bill is $10.

What are you solving for?

Percent (%)

Of what number?

Result

Worked as: 200 × 15 ÷ 100 = 30
Decimal form of the percent: 0.15

Common percentages of 200

Percent	Value
5%	10
10%	20
15%	30
20%	40
25%	50
50%	100

Looking at how much something changed? That's a different question — use the percentage increase calculator.

15% of 200 is 30. Percentages answer two different questions, and this page does both: what is X% of Y (200 × 15 ÷ 100 = 30) and X is what percent of Y (30 ÷ 200 × 100 = 15%). Pick the question, type two numbers, and the arithmetic is shown alongside the answer.

The two questions a percentage answers

Every percentage problem is one of these:

What is X% of Y? — you know the rate and the total, you want the part. 15% of 200 = 30.
X is what percent of Y? — you know the part and the total, you want the rate. 30 out of 200 = 15%.

A third question — how much did this change — is different enough to have its own page: the percentage increase calculator handles 50 → 75 being a 50% rise, and why 75 → 50 is not a 50% fall.

How to find a percentage of a number

value = base × percent ÷ 100

Worked example, 15% of 200: 200 × 15 = 3,000, ÷ 100 = 30. The shortcut is to move the decimal: 15% is 0.15, and 200 × 0.15 = 30.

That's the shape of a sales tax. On a $250 purchase at 7%, the tax is $250 × 0.07 = $17.50, and the total with tax is $267.50. Notice the tax is computed on the pre-tax price, not on the total — a common way to overpay yourself.

How to find what percent one number is of another

percent = part ÷ whole × 100

Worked example, 30 out of 200: 30 ÷ 200 = 0.15, × 100 = 15%. Same numbers, opposite direction — which is the fastest way to check your own work: if 15% of 200 is 30, then 30 is 15% of 200.

One case has no answer: when the whole is 0, the percentage is undefined, because there's nothing to take a share of. This calculator says so instead of showing infinity.

Percentage points aren't percent changes

This is where published numbers get misread. If a rate goes from 10% to 15%, that's 5 percentage points — but it's a 50% increase in the rate itself, because 15 is half again as much as 10. Both statements are true and they sound nothing alike, so it's worth knowing which one a headline means. The percentage increase calculator does the second kind.

How to use this calculator

Tap the question you're solving — the two buttons swap the inputs for you.
Type the two numbers (15% of 200 is filled in, so the page shows a result immediately).
Read the result and the worked line under it — that's the arithmetic you'd write down.
Open the chart to see what the usual percentages of your number come to.

Frequently asked questions

What is 15% of 200?

30. Multiply 200 by 0.15 — it's the calculation this page opens with.

How do I work out what percentage one number is of another?

Divide the part by the whole and multiply by 100. For 45 out of 60: 45 ÷ 60 = 0.75, × 100 = 75%.

What is 20% of 50?

10. It's the same pattern people use for tips: 20% of a $50 bill is $10.

How do I add a percentage to a number?

That's a different operation — 200 plus 15% is 230, not 30. Use the percentage increase calculator, which shows the result and the amount added.

Why does the calculator say the percentage isn't defined?

Because the whole (the second number) is 0. Taking a share of zero has no answer, so we say nothing rather than print infinity.

Data sources: Both formulas on this page are arithmetic definitions rather than published rates, so every figure here can be reproduced by entering the same two numbers. The sales tax example uses a generic 7% for illustration; your local rate is set by your state and locality. Related tools: percentage increase calculator, inches to cm converter, all math calculators.