How to calculate percentage of a number?

Multiply the number by the percentage rate and divide by 100. Formula: Result = (Number × Percentage) ÷ 100. For example, 20% of 150 = (150 × 20) ÷ 100 = 30. Our calculator does this instantly as you type.

How do you calculate percentages?

There are three main ways: 1) To find X% of Y: multiply Y by X and divide by 100. 2) To find what percent X is of Y: divide X by Y and multiply by 100. 3) To find percentage change: subtract the old value from the new, divide by the old value, and multiply by 100.

What is the percentage formula?

The basic percentage formula is: Percentage = (Part ÷ Whole) × 100. To find a percentage of a number: Result = (Whole × Percentage) ÷ 100. For percentage change: Change % = ((New - Old) ÷ Old) × 100.

How to calculate amount in percentage?

To express an amount as a percentage of a total, divide the amount by the total and multiply by 100. For example, if you scored 45 out of 60: (45 ÷ 60) × 100 = 75%. This tells you that 45 is 75% of 60.

How to calculate percentage change?

Use the formula: ((New Value - Old Value) ÷ Old Value) × 100. If the result is positive, it's an increase; if negative, it's a decrease. From 80 to 100: ((100 - 80) ÷ 80) × 100 = 25% increase.

Free Online Percentage Calculator

Five calculators in one: calculates percentages, reverse-solves them, finds the whole, or compares two values.

Calculate Percentages in Common Phrases

1What is X% of Y? Find what a given percentage of a number is.

Percent

of Number

Result:–

2X is What % of Y? Find what percentage one number is of another.

Value

is what % of

Result:–

3X is P% of What? Work backward from a part and its percentage to find the whole.

Value

is Percent

of What:–

Percentage Change Calculator

Find the percentage increase or decrease between two values.

From

Change:–

Percentage Difference Calculator

Compare two values with neither treated as the "original."

First Value

Second Value

Absolute Difference:–

Percentage Difference:–

Whether you're splitting a restaurant bill, checking a discount at checkout, or working through a homework problem, a percentage calculator turns a fraction-of-100 question into the exact number you need in one step. Instead of doing the arithmetic by hand, you plug in the two values you already know and find percentage answers instantly — accurate, without pulling out a pen and paper. This guide walks through the underlying formula, why percentage change and percentage difference aren't interchangeable, and how those same numbers turn into real discounts, margins, and grades. For more number-crunching tools, try math calculators at Joteo.

What Is a Percentage Calculator?

A percentage calculator works by treating three numbers as interchangeable — a part, a whole, and a percent. Give it any two, and it solves for the third using the same short chain of division and multiplication you'd use by hand. A percentage itself is just a ratio written as a fraction of 100; the word literally means per hundred. Every fraction splits into a numerator (the part) and a denominator (the whole) — a percentage is simply that same fraction rescaled so the denominator is always 100. If 25 out of 100 people vote yes, that's 25% — a quarter of the whole, a percentage of a whole in the most literal sense. You'll usually see it written with a percent sign (%), though "percent" and "pct" work as shorthand too. Whether you calculate percentages for a grade, a tip, or a stock report, the underlying mechanics never change.

What Is a Percentage?

Percentages let you compare things that don't share a common scale — 12 out of 60 and 40 out of 200 both reduce to the same 20%, even though the raw numbers look nothing alike. That's the entire value of expressing a number as percentage-based calculations rather than a raw fraction: it puts every comparison on the same 100-point scale, whether you're comparing exam scores, discounts, or survey results.

How the Percentage Formula Works: Percentage Calculator in Excel

Every percentage calculator like this one runs on the same three-number relationship, and once you know the formula percentage calculators use, you can check its work by hand in seconds.

The Basic Percentage Formula

The percentage formula has three interchangeable forms, depending on which value you're solving for — which is exactly the shortcut every percentage calculator uses under the hood:

Percentage of a number: multiply the whole by the decimal form of the percent.
What percent one number is of another: divide the part by the whole, then multiply by 100.
Finding the whole: divide the part by the decimal form of the percent.

Written as an equation:

$$ \frac{X}{Y} \times 100 = P\% $$

Diagram showing the percentage formula: Whole multiplied by Percent equals Part, rearranged three ways — The same formula, rearranged for whichever value you're solving for.

For example, if 12 of 60 servings contain a nutrient, divide 12 by 60 to get 0.2, then multiply by 100 to convert that decimal into 20%. That last step — multiply by 100 — is the one people forget, and it's the difference between reporting 0.2 and reporting the correct 20%. Going the other direction, if you already have a percent and need the decimal, you divide by 100 instead: 20% ÷ 100 = 0.2, and that decimal form is what most formulas expect as input. Knowing how to calculate percentage by hand this way also makes it easy to sanity-check any online tool's answer.

How to Convert Percentage to Decimal or Fraction

Because this is a free percentage calculator guide, you can practice every conversion below without any signup. It helps to be fluent converting between percent, decimal, and fraction — here's a quick-reference cheat sheet:

Percent	Decimal	Fraction
10%	0.10	1/10
25%	0.25	1/4
50%	0.50	1/2
75%	0.75	3/4
100%	1.00	1/1

Decimal to Percent

To convert decimal to percent, multiply by 100 and add a percent sign: 0.44 × 100 = 44%.

Percent to Decimal

To go from percent to decimal, remove the percent sign and divide by 100: 15.6% ÷ 100 = 0.156.

Fraction to percent: divide the numerator by the denominator, then multiply by 100 — 4/5 = 0.80 × 100 = 80%.
Percent to fraction: divide by 100 and simplify — 30% = 30/100 = 3/10.

Percentage Difference vs. Percentage Change vs. Percent Error

A percentage calculator built for everyday money math usually offers separate modes for percentage change and percentage difference, and it's worth knowing why they're not the same calculation.

Percentage Difference Formula: Percentage Calculator Difference

This calculation compares independent measurements against each other, with neither one treated as the "original" baseline — useful when you're not tracking a value over time.

$$ PD = \frac{|V_1 - V_2|}{\frac{V_1+V_2}{2}} \times 100 $$

For 10 and 6, that's |10−6| ÷ 8 × 100 = 50%. The formula treats V₁ and V₂ symmetrically, so swapping them gives the same result. This is distinct from percent error, which measures a single experimental value against a known true value rather than comparing two independent measurements.

Percentage Decrease and Percentage Increase Calculator

This kind of change is different: it always measures relative to an original value, comparing an initial value to a new value.

$$ \%\Delta = \frac{V_{new} - V_{old}}{V_{old}} \times 100 $$

A jump from 100 to 150 is a percentage increase of 50%, while 150 dropping back to 100 is a percentage decrease of about 33.3% — same two numbers, opposite direction, because the base changes. This is exactly what most "change" calculator modes are built for.

Chart comparing a 100 to 150 increase (+50%) against a 150 to 100 decrease (-33.3%), showing the two percentages are not equal — Increase and decrease use different starting values, so they're never mirror images of each other.

Percentage Points vs. Percentage Change

Don't confuse the two: if a rate moves from 25% to 30%, that's a 5 percentage point increase, but it's a 20% relative increase (5 ÷ 25 × 100). Headlines often blur this — a jump in percentage points is an absolute difference, while percentage change is always relative to the starting number.

Using Percentages for Discounts and Business Pricing

Percentage calculators earn their keep in everyday money math — pricing, profit, tax, and tips all reduce to the same underlying formula with different labels on the numbers.

Discounts and Discounted Price

A discount calculator finds the discounted price by subtracting a percent of the original price: a $150 jacket at 10% off saves a $15 amount, for a discounted price of $135. Run the same calculator in reverse when you only know the sale price and need to reconstruct the original.

Markup, Margin, and Profit Percentage

Markup and margin get mixed up constantly: one measures profit against cost price, the other against selling price — the same $50-cost, $100-price item is a 100% markup but only a 50% margin. Retailers chasing their true profit percentage almost always mean the latter. A commission works the same way, just paid out instead of pocketed.

Discount calculator – subtracts a percent off the original price.
Markup calculator – adds a percent on top of cost price.
Margin calculator – works backward from selling price to find profit margin.
Commission calculator – applies a percent to a sale to find the payout.
Tip calculator – applies a percent to a bill total.

Every one of these calculators reduces to the same core percentage formula, just with different labels on the inputs.

VAT, Sales Tax, and Tips

Adding tax works the same way in reverse. To add VAT, multiply the price by (1 + VAT%/100); a $100 item with 20% VAT costs $120. In the US, sales tax is calculated identically, just with a different label and rate — some VAT calculators even let you toggle between an inclusive and exclusive VAT rate. A tip calculator applies the same multiply-by-percent logic to a restaurant bill — 15% of a $45 tab is a $6.75 tip amount, whether you call it a tip, a gratuity, or a service charge.

Find Percentage: Common Problems and Worked Examples

Most everyday percentage problems — often framed as a word problem in a textbook — rely on the same handful of percentage computations. Here's how to recognize each shape and solve it without a percentage calculator if you need to.

Finding the Percentage of a Number

"What is 15% of 200?" Multiply: 200 × 0.15 = 30. This is the most common of all percentage word problems, and it's the one behind tips, taxes, and discounts alike.

Identify the whole (200) and the percent (15%).
Convert the percent to a decimal: 15 ÷ 100 = 0.15.
Multiply: 200 × 0.15 = 30.

Finding What Percent One Number Is of Another

"40 eggs, 12 are brown — what percent is that?" Divide the part by the whole, then multiply by 100: 12 ÷ 40 = 0.3, and 0.3 × 100 = 30%. Flip the question — "Y is P percent of what?" — and you divide instead: 9 ÷ 0.6 = 15, so 9 is 60% of 15.

Calculating an Average Percentage from Multiple Values: Average Percentage Calculator

To find an average percentage across several results — say, three test scores of 80%, 90%, and 100% — add the percentage values together and divide by the count: (80 + 90 + 100) ÷ 3 = 90%. This only works cleanly when each of the values is out of the same total; average percentages from different-sized groups need a weighted approach instead.

Why You Need a Percent Calculator in Everyday Life

Percentages show up far outside any percent calculator window, in fields as different as mathematics classrooms and corporate balance sheets.

Percentages in Finance and Business: Percentage Calculator Money

In personal finance, percentages set interest rates on loans and savings, determine tax brackets, and describe portfolio returns. In business management and economics, they track profitability, guide pricing decisions, and — in industries built around affiliate programs — calculate commission payouts on every sale. Behind the scenes, most spreadsheet-driven data analysis and everyday financial calculations still lean on this same percent-of-a-whole logic.

Percentages in School, Shopping, and Statistics: Percentage Calculator of Marks

In the classroom, exam scores and final grades are almost always reported as percentages. At the grocery store, shopping discounts and nutrition food labels both lean on the same math. And across statistics and mathematics more broadly, percentages remain the simplest way to compare interest rates, survey results, or any other data expressed as a share of a whole.

Frequently Asked Questions

Q.How to calculate percentage?: To calculate a percentage, divide the part by the whole and multiply by 100. For example, to find what percentage 25 is of 200: (25 ÷ 200) × 100 = 12.5%. To find a percentage of a number (like 15% of 80), multiply the number by the percentage and divide by 100: (80 × 15) ÷ 100 = 12.
Q.How to calculate percentage of a number?: Multiply the number by the percentage rate and divide by 100. Formula: Result = (Number × Percentage) ÷ 100. For example, 20% of 150 = (150 × 20) ÷ 100 = 30. Our calculator does this instantly as you type.
Q.How do you calculate percentages?: There are three main ways: 1) To find X% of Y: multiply Y by X and divide by 100. 2) To find what percent X is of Y: divide X by Y and multiply by 100. 3) To find percentage change: subtract the old value from the new, divide by the old value, and multiply by 100.
Q.What is the percentage formula?: The basic percentage formula is: Percentage = (Part ÷ Whole) × 100. To find a percentage of a number: Result = (Whole × Percentage) ÷ 100. For percentage change: Change % = ((New - Old) ÷ Old) × 100.
Q.How to calculate amount in percentage?: To express an amount as a percentage of a total, divide the amount by the total and multiply by 100. For example, if you scored 45 out of 60: (45 ÷ 60) × 100 = 75%. This tells you that 45 is 75% of 60.
Q.How to calculate percentage change?: Use the formula: ((New Value - Old Value) ÷ Old Value) × 100. If the result is positive, it's an increase; if negative, it's a decrease. From 80 to 100: ((100 - 80) ÷ 80) × 100 = 25% increase.